Prenatal Testing in the First Half of Pregnancy

0:00You are listening to the Pregnancy Podcast with the Nessomert. Hello! Thank you for tuning into the Pregnancy Podcast. In today's episode, we're talking about prenatal testing in the first half of your pregnancy. Prenatal testing starts the moment that you find out you're pregnant, and then it continues throughout your entire pregnancy. Seems like there is a never-ending string of tests. Some tests screen for conditions that you may have, others look at your baby's development and their genetics. These tests are valuable tools, but they can also be a source of real anxiety and confusion. There's a lot of different tests that go by a lot of different names, and a ton of information to navigate. This episode is an evidence-based guide to every

1:00test that's offered in the first half of your pregnancy. We'll walk through each one that you may be offered all the way through your anatomy ultrasound. We'll talk about what each test can tell you, how accurate it is, and how to make informed decisions. By the end of this episode, you will have a clear understanding of all of your options, and you will feel confident having these conversations with your doctor or midwife. Then there will be a companion episode that will cover prenatal testing in the second half of your pregnancy. You can see the full article and all of the resources for this episode at pregnancypodcast.com slash prenatal testing. If you feel overwhelmed by your prenatal testing options, you're in the right place. Today's episode is a comprehensive guide to every test offered in the first half of pregnancy. The work that goes into an episode

2:02like this is significant, and pregnancy podcast premium is one way that listeners can support this work directly, and premium members get the entire library of episodes ad-free on every topic that you will run into from the minute you find out your pregnant through life with a new baby. Check out pregnancypodcastpremium at pregnancypodcast.com slash premium. VTech is the number one baby monitor brand in North America, and trusted by millions of families. The VTech VM5266 baby monitor has a 5-inch color screen, pan, tilt, and zoom from the parent unit, and sound activated soothing that turns on a night light when your baby stirs. This is available at Target and you can check it out at pregnancypodcast.com slash VTech. That's

3:04V-T-E-C-H. H-Sheep organics makes amazing 100% clean natural pregnancy products. From taking care of your skin to treating common symptoms like stretch marks with clinically proven ingredients, H-Sheep has you covered. Every product comes with a 100-day happiness guarantee, try it risk-free, and if you're not 100% happy with your purchase, simply send them an email, and they'll get you a refund no questions asked. Check out H-Sheep organics and save 10% when you go to pregnancypodcast.com slash eight sheep. Before we get into the test themselves, we have to touch on one thing that expecting parents feel, but that is rarely talked about. There is a certain low-level anxiety that runs underneath pregnancy, and a lot of this is tied

4:06to testing. You wait for an early ultrasound to confirm a heartbeat, then you're waiting for genetic screening results, then you're waiting for your anatomy scan, and the results from that. Even after every test comes back normal, there's still a sense that you don't truly know everything is okay until you're holding your baby in your arms. This is something that I felt tremendously with both of my pregnancies, and if you were filling it too, I want you to know that you're not alone. You can't do anything about the waiting, that's just a built-in mechanism with prenatal care, but you can walk into every appointment informed and prepared. The more you understand what each test is and why it matters, the less space there is for anxiety. So the goal of this episode is really to give you that foundation, so that way every testing decision you make feels like your own, and you can feel confident about it. Prenatal tests fall into a few general

5:11categories based on what they're looking for. Some tests monitor your health during pregnancy, these track things like blood pressure, glucose levels, infections, anemia, then there are other tests that focus on your baby. They look at their growth, development, and genetics. Then you have a third group of tests that test for conditions that could influence your birth. All of these tests are tools that your care provider is using to build a picture of your pregnancy and your risk factors. Some are routine and essentially universal, others are optional and may depend on your personal circumstances, your family history, and your preferences. One of the most important distinctions in prenatal testing is the distinction between a screening test and a diagnostic test. This is really important to understand. A screening test tells you the likelihood that a condition is present, but it doesn't give you a definitive yes or no.

6:17Instead, it's combining information from the test along with other factors like your age, your medical history, and then it uses all of that data to estimate risk. A positive screening result doesn't mean that your baby has a particular condition. It just means that there is a higher chance of a positive result, and that means that it is worth considering further testing. Further testing would be diagnostic, and a diagnostic test can actually give you a definitive answer. It confirms whether a specific condition is actually present. Diagnostic tests for genetic conditions are invasive, and they carry some risk. And for this reason, providers typically only offer them after a positive screening result, or when there's a need that's suggested by your family history. This distinction really matters, because if you get

7:18back a positive screening result, that can feel very scary in the moment, and it's very easy to jump to conclusions and think about worst case scenario. But a screen is not a diagnosis, and many people who receive a positive screen test will go on to have a negative diagnostic test, and perfectly healthy babies. As a result, the screen is really the starting point for further conversation with your care provider. It doesn't give you direct answers. Another useful distinction is whether a test is invasive or non-invasive. Non-invasive tests don't pose any risk to you or your baby. If you are anxious about needles, I understand that a blood draw may not feel particularly non-invasive, and that's fair, I understand I'm terrified of needles. One thing to keep in mind, if blood draws are difficult for you, let your doctor or midwife know, and ask to have someone

8:20who's experienced draw your blood. The last thing you want to do if you are afraid of needles is to have a first day in turn trying to find a vein. Then you have invasive tests. These carry some risk because they involve accessing fluid, tissue, or cells from inside your uterus, and the only way to do that is with a needle. The main invasive tests in pregnancy are a Chorionic Villas sampling, a CVS, an Amniocentesis, and a Chorocentesis. Remember though, most prenatal testing is non-invasive, and providers typically only offer invasive tests after a positive screen result, or when there is a known genetic risk in your family. Another thing that you have to understand is that no test is 100% accurate, and to really wrap your head around this, there's a few key terms that will help you make sense of every test that we talk about. First, you have

9:25sensitivity. This is how often a test correctly identifies a condition when it's actually present. As an example, if you have a test with a 99% sensitivity, that means it correctly flags 99 out of every 100 babies. The remaining one baby would receive a false negative, meaning that the test missed the condition. Then, on the flip side, you have specificity. This is how often a test correctly rules out a condition when it's not present. As an example, a test with 99% specificity correctly clears 99 out of 100 babies that don't have a condition, but there would be one person that would get a false positive. In other words, then the test would flag a condition that's not actually there. Then, you have positive predictive value. This is a term that matters the most,

10:28and that's the probability that a positive result is actually a true positive. Positive predictive value depends a lot on how common the condition is in the group that's being tested. For very rare conditions, even a highly accurate test can have a surprisingly low positive predictive value. This means that a positive result is more likely to be a false alarm than people often realize. And we'll come back to this when we're talking about genetic screening because it's really essential to understand what a positive result on a screen test really means. Let's get into some of the standard testing. First is a urine analysis. This is a very quick, non-invasive test that can give your doctor a midwife a lot of information. What you'll do is provide a urine sample, then your care provider will dip a test strip into that or send it to a laboratory.

11:30They will check for your levels of glucose, proteins, ketones, and bacteria. These markers can flag risk for things like urinary tract infections, kidney issues, gestational diabetes, dehydration, and preeclampsia. The American College of Obstetricians and Gynecologists recommends a baseline urine test at your first prenatal visit, and then you're typically going to have at least one other one. Additional urine tests really depend on your care provider and whether anything in your initial results weren't tracking. Another thing that happens at your first appointment is a blood draw. And this checks for a lot of different things. A single sample of your blood can tell your care provider your blood type, your immunity for certain infections, and your risk for several conditions. In addition, you may need additional blood tests later in your pregnancy. These can monitor for anemia. They can screen for infections if a concern comes up.

12:37So let's talk really about what's involved in a typical prenatal blood panel. First is your blood type A, B, A, B, or O. This does not affect your pregnancy, but it would be relevant in the event you needed a blood transfusion. What's most relevant to your pregnancy is your RH factor. This is a protein on your red blood cells, and you're either RH positive, which is the most common, or RH negative. RH negative status varies significantly by ethnicity. According to a very large study of over 3 million donors from the American Red Cross, about 17% of white Americans are RH negative, and that decreases a lot in other groups. About 7% of black and Hispanic Americans are RH negative, and the rates are even lower in people of East Asian descent. If you and your baby have different

13:39RH statuses, so you are RH negative and your baby is RH positive, there's a possibility of an RH incompatibility. Typically, this doesn't cause problems. So if you are RH negative and your baby's RH positive, the first time that your blood encounters your baby's blood, your immune system produces antibodies. Typically, this is going to happen at birth, and we call this first exposure sensitization. Sensitization can also happen through other events that could expose your blood to your baby's blood. This would be things like a miscarriage, an ectopic pregnancy, with an amniocentesis, or a CVS, or with abdominal trauma. Once your immune system has been sensitized, it stays primed to produce antibodies the next time that it encounters RH positive blood. So as a result, in subsequent pregnancies, those antibodies could cross the placenta,

14:44and they could attack your baby's red blood cells and cause serious complications. In order to prevent this, there is a standard treatment for RH incompatibility, and that is with Row D Immune Globulin. This is most commonly known by the brand name RoGam. RoGam blocks this initial immune response, so your body never builds up antibodies in the first place. Typically, if this is something that you will be given, you'll get it around 28 weeks, and then you would receive another dose after birth if your baby is RH positive. It's possible that you would also get additional doses after an event that could expose your blood to your baby's blood, things that would involve bleeding, trauma, miscarriage, or an invasive test like an amniocentesis. One thing you need to keep in mind here, if the baby's father is also RH negative, then your baby will also be RH negative,

15:50which means that an RH incompatibility does not apply. That's assuming that you are 100% certain on the paternity, because paternal status may not always be known with certainty, ACOG recommends fetal RHD genotyping with a cell-free DNA test as the most reliable way to determine your baby's actual RH status. Using cell-free DNA actually analyzes fragments of your baby's DNA that circulate in your bloodstream, and this will allow your provider to determine your baby's RH status as early as 10 weeks. So if the test confirms that your baby is RH negative, then Rogam is not needed. About 40% of RH negative mothers carry an RH negative baby. So in the past, if you were RH negative, they would just routinely recommend Rogam with this new information,

16:54a meaningful number of women could potentially avoid unnecessary Rogam doses. ACOG now formally supports the use of cell-free DNA for this purpose. Cell-free DNA is very accurate for this, it has a pooled sensitivity of over 99% and a specificity of over 98%. So in other words, this is a very accurate test. One thing to note in 2023, there was actually a Rogam shortage in the United States. And as a result, ACOG issued a practice advisory supporting cell-free DNA based genotyping as a way to conserve supply. Because if you could just rule out that somebody needed Rogam, then that would conserve that medication for somebody that did require it. Despite all of this, using cell-free DNA to determine a baby's RH status is not standard and routine everywhere in

17:59the United States availability for this will vary on practice and insurance coverage. This is something though that has been routine in parts of Europe for many years. So if you are RH negative, it is worth asking your doctor, midwife, whether a cell-free DNA test is available to determine the RH status of your baby. And we'll talk much more, there's a lot more things that come out of the cell-free DNA test and we will talk about all of that. Another thing that happens at your first appointment with that blood panel is they're also screening for a handful of infectious diseases. And this is important because some infections can cross the placenta or be transmitted during birth. And many of these are treatable with early detection. Most of these tests are universal and run as a standard panel when they take your blood. Typical panel includes HIV, syphilis, hepatitis B, and often chlamydia and gonorrhea. They may also check your immunity

19:06to robella, that's the German measles, and varicella, which is chickenpox. These viruses can cause serious complications for your baby if you contract them during pregnancy. So if you're not immune, your care provider will likely recommend vaccination after you have your baby. Your blood also provides a complete blood count or a CBC. Your iron levels and hemoglobin are determined that tells your provider how well your blood carries oxygen. In addition, it's going to show whether you were at risk for anemia. Anemia is a condition where you don't have enough healthy red blood cells to carry adequate oxygen throughout your body. And the most common cause of anemia and pregnancy is an iron deficiency. This happens because your blood volume is expanding significantly and you have increased iron needs. And if you're not meeting those, then you could be deficient.

20:09Other less common causes of anemia include folate or vitamin B12 deficiency and certain inherited blood disorders. If your levels are low, your provider may recommend dietary changes or an iron supplement. And this is a test that's typically repeated later in pregnancy. If you're found low early on, and this usually happens around the time of gestational diabetes screening. Another thing they look for in your blood sample is glucose levels. And that gives your provider a baseline. If you have elevated levels early on, then your care provider may recommend that you get screened for gestational diabetes earlier than it is routinely offered. Next, let's talk about carrier screening. This is a genetic test that's going to check whether you carry genes for specific inherited conditions. Most of these are recessive. And that means that a

21:13child would have to inherit the gene from both parents in order to have the condition. If only one parent is the carrier, a child is typically not at risk, though that could mean that your child also becomes a carrier. Carrier screening tests for conditions like cystic fibrosis. That's a lung and digestive disease for spinal muscular atrophy. That's a motor neuron condition. And then things like sickle cell disease, tasex disease, and various forms of thalassemia. Those are blood disorders. Most of these conditions are individually very rare. But being a carrier is much more common than having the condition. For example, cystic fibrosis affects approximately 1 in 2500 to 3500 white newborns in the United States. The reason we're bringing up ethnicity is that there are much lower rates in other ethnic groups. But about 1 in 25 people of European descent

22:20carry a cystic fibrosis gene variant. Carrier screening is most often done during pregnancy, especially at the first prenatal appointment. This is a simple blood or saliva test. And if you carry a specific condition, then they may want to test your partner to determine the actual risk to your baby. You could also do carrier screening before conception. That's going to give you the most flexibility. But that's not the timing that most parents come into this test. And there's nothing wrong with starting this conversation during pregnancy. So if you didn't do any carrier screening before getting pregnant, do not worry. According to the American College of Obstetricians and Gynecologists, every patient who is pregnant or considering pregnancy should be offered carrier screening for cystic fibrosis and spinal muscular atrophy. They also recommend a complete

23:24blood count in screening for conditions like sickle cell disease and thalassemia. Beyond these core recommendations, your provider may offer an expanded carrier screening panel. And these can test for anywhere from dozens to hundreds of conditions. The landscape of carrier screening has shifted a lot in recent years. Historically, providers used an ethnicity-based approach because often the prevalence of these things vary depending on ethnicity. For example, Taysac's disease was routinely offered to people of Ashkenazi, Jewish descent. But this approach has limitations, especially when we have an increasingly multi-ethnic population, where people do not always fit neatly into one category. So as a result, the American College of Medical Genetics and Genomics has moved towards what it calls a tiered approach.

24:27So they recommend all patients, regardless of ethnicity, be offered tier three screening. This panel includes 113 conditions chosen for their severity and carrier frequency. One important thing to know about carrier screening is in a recent study of over 20,000 patients that were tested with that gene panel that tests for 113 different genes. 57.5% of patients were carriers for at least one of the conditions on the panel. So it's likely that you could be a carrier for something and that really underscores the importance of your partner testing if you pop up positive for any of those genes. The practical take away with carrier screening is that this is increasingly available and it is increasingly covered by insurance. If this is something that you were interested in, ask your care provider what panel

25:31they offer and whether a broader panel is available if you want to be tested for additional things. And remember a positive result does not mean that your baby will have a condition. It just means that further testing for your partner could be a reasonable next step. If both of you test positive, then you may consider meeting with a genetic counselor that can help you understand what those results mean. Beyond carrier screening, there's a separate category of prenatal genetic screening that focuses on chromosomal abnormalities. These are conditions that happen when a baby has an extra or missing chromosome, which is known as annual poidie. The most well known is trisomy 21 or Down syndrome. This occurs when a baby has an extra copy of chromosome 21. There are also annual poidies like trisomy 18, which is Edward syndrome and trisomy 13. In addition, chromosomal

26:39abnormalities also include conditions involving sex chromosomes like turner syndrome and client-felter syndrome. ACOG and the Society for Maternal Fetal Medicine recommend that every pregnant patient learn about both screening and diagnostic testing options. The goal is for every patient to be able to make their own decision regardless of their age or baseline risk. This is a big shift from older guidelines, older guidelines limited routine screening to patients over 35 or that had risk factors, and now the decision of whether or not to pursue testing and which approach to take is now much more patient centered. Cell-free DNA screening is the most accurate screening test for common chromosomal abnormalities. This is a test you may have heard referred to as an NIPT

27:40or a NIPT. That stands for non-invasive prenatal testing. However, that term is being phased out because it can falsely imply that the test is diagnostic and it is not, it is a screening test. But this is highly accurate and a positive result still requires confirmation through diagnostic testing. So as a result, the more current term is simply cell-free DNA screening or prenatal screening with cell-free DNA. So what is this? Well, here's how it works. During pregnancy, there are fragments of your baby's DNA that are primarily from the placenta that circulate in your bloodstream. So they can take a simple blood draw from you and isolate and analyze that DNA from your baby. There's no risk to you or your baby from the test itself. It's considered

28:40non-invasive and this can be done as early as 10 weeks of pregnancy. Then results are typically available within one to two weeks. The core goal with cell-free DNA is to assess risk for trisomy 21, trisomy 18 and trisomy 13. Plus, most labs will offer screening for sex chromosome annual poise like Turner syndrome or Kleinfelter syndrome. Almost all labs will determine the biological sex of your baby as part of that result. That's super exciting. Usually you'd have to wait for the anatomy scan ultrasound, which isn't until about the halfway point. Some labs will also offer screening for micro deletions. These are very small missing pieces of chromosomes that can cause specific syndromes. The Society for Maternal Fetal Medicine has made a strong recommendation. This has also been endorsed by ACOG that cell-free DNA screening for the

29:48common trisomies be made routinely available to all obstetric patients. In addition, they recommend that sex chromosome annual poise screening be opt-in. The reason for that is that the false positive rates are higher under these conditions. For micro deletions, the Society for Maternal Fetal Medicine recommends against routine cell-free DNA screening. Instead, patients that are interested in information on micro deletions should be offered diagnostic testing. Let me explain why this is. Accuracy of this test for the common trisomies is very high. A systematic review and meta-analysis of over 100 studies found a sensitivity of over 99 percent for trisomy 21, over 97 percent for trisomy 18, and over 97 percent for trisomy 13. Specificity was also

30:52very high across all three. These figures come from research built on a trial called the Next Trial. This compared cell-free DNA to standard first trimester screening in nearly 16,000 women across an average risk population. So what they found is that cell-free DNA outperformed standard screening even in an average risk group. This finding is really the foundation behind ACOG shifting their recommendation for all patients getting cell-free DNA. Cell-free DNA behaves differently across different populations. In a hypothetical high-risk population of 10,000 pregnancies, researchers estimated cell-free DNA would correctly identify 324 cases of Down syndrome. It would miss 9 and produce 31 false positives. This is in a group that is

31:58considered high risk. In a hypothetical lower risk population of 100,000 pregnancies, it would identify 417 cases with 94 false positives. To translate this into plain English, this test is more accurate in a higher risk population. And that's because the positive predictive value depends on how common a condition is in the group. We touched on positive predictive value because the common trisomies 21, 18, and 13 are relatively rare even a highly accurate screening test can produce false positives. This is why I have mentioned multiple times in this episode to not panic if you get a positive result on a screening test. A positive cell-free DNA result for trisomy 21 in a younger, lower risk patient has a positive predictive value

33:04around 80 to 90 percent. So that means that 10 to 20 percent of positives are false alarms. And for more rare conditions and micro-deletions, positive predictive values are much lower. There was an analysis done by the New York Times that looked at the most commonly offered micro-deletion tests and they estimated that positive results were incorrect about 85 percent of the time. So because of all of this, current guidance does not recommend routine micro-deletion screening and any positive screening result deserves very careful conversation with your doctor or midwife or a genetic counselor before jumping to conclusions or panicking. A few other important notes on cell-free DNA. This is a first-line option for screening for trisomy 21 with twins.

34:05If you have triplets or more than three babies, cell-free DNA would not be recommended. It's also possible that your cell-free DNA test results come back as non-reportable. That means that the lab could not produce a clear result. And that can happen for a few reasons. If there's low fetal fraction, so there's not enough of your baby's DNA in the sample. A high maternal body weight and other factors can also affect the result. Some studies have associated a non-reportable result with a slightly higher risk for annual ployty. The research on that is mixed. So the current guidance recommends following up with genetic counseling if you get that non-reportable result. In addition, you may consider further evaluation if you get that non-reportable result. And although we covered this a little bit earlier, remember, cell-free DNA can also detect your baby's R-H status. So it can tell you whether

35:11their blood is R-H positive or negative. One side note, I debated whether or not to include this in this episode, but I think it's something worth being aware of. The labs that perform cell-free DNA screening, the companies that produce these tests have a very large financial interest in expanding the use of these tests. As a result, some of the messaging around prenatal screening reflects that. These companies have every incentive for this test to be routinely recommended to every single pregnant woman. The cell-free DNA test is a useful tool and current guidelines do recommend offering this to all patients, but knowing that there are commercial incentives in the system and this isn't just for the cell-free DNA test. This could apply to a lot of different things, may help you approach this with a more balanced viewpoint.

36:13Next up, we're going to talk about alternatives to cell-free DNA and the anatomy scan. Before we do that, I'd like to thank the sponsors that have supported this episode. A lot of companies have exclusive discounts for pregnancy podcast listeners, and you can always see discounts and promo codes at pregnancypodcast.com slash resources. VTEC is the number one baby monitor brand in North America and is trusted by millions of families. And when you're trying to get your baby to sleep, every little thing matters. The right sound, a soft light, the ability to soothe them without walking back into the room every time can make a big difference. And a good baby monitor can actually help with that. The VTEC VM 5266 video baby monitor is designed with sleep in mind.

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38:17of families. You can check out the VM 5266 at Target and see my favorite products from VTEC at pregnancypodcast.com slash VTEC. Let's get back to today's episode. Before Self-Free DNA became widely available, there were serum-based screening tests for genetic screening. These are still used in specific situations when a self-free DNA would be not available if it's not covered by insurance or cannot be performed reliably. And these are options that you may have available. The first trimester screen combines a blood test of two markers from you with an ultrasound measurement of your baby's Neucle Translucency. Neucle Translucency is the fluid collection at the back of your baby's neck.

39:22Babies that have down syndrome often have an increased amount. This is a test that's done between 11 and 13 weeks, and the combined detection rate for the common trisomies is roughly 85 percent with a false positive rate of about 5 percent. So you can see this is less accurate than self-free DNA. There's also a quad screen. This is a maternal blood test that measures four substances. It's looking at alpha-fetoprotein, HCG, Estriol, and Inhibin A. This is done between 15 and 22 weeks. In addition to screening for trisomies 21 and 18, it can also flag risk for neural tube defects like Spina Bifida. This is somewhat less accurate than the first trimester screen, which also makes it much less accurate than self-free DNA. Then you have an integrated screen

40:25that combines both the first and second trimester tests, and that has a higher detection rate than either of the tests alone. But another issue with that is that results are not available until after the second trimester component is complete. So there's quite a gap between taking those tests and getting results. If you're choosing between self-free DNA and serum screening, self-free DNA is more accurate for the common trisomies. But there is something that serum screening can offer that self-free DNA does not, and that is the risk for neural tube defects. The current guidance is that you should have one screening approach, not multiple simultaneously. And that's because multiple screens can produce contradictory risk estimates. So typically, you're not going to do self-free DNA, and one of these tests you would pick one or the other.

41:26Next, we have the anatomy scan. This is a detailed ultrasound, typically done between 18 and 22 weeks, and the technician that does this will take a very detailed look at your baby's organs, they'll look at specific measurements, structural development. This is one of the most significant tests during your pregnancy, and that's because it's checking for a wide range of structural abnormalities. And this is often the point where patients would find out the biological sex of their baby if they did not do a self-free DNA test. The anatomy scan also helps identify neural tube defects, heart defects, and other structural differences. Sometimes the anatomy scan picks up what is called soft markers. These are small findings that can occur in some chromosomal conditions, but they also occur frequently in healthy babies.

42:30In the era where almost everyone is getting a self-free DNA test, having an isolated soft marker from an anatomy scan with a normal self-free DNA test is typically considered a normal variant. Most babies with these findings are completely healthy, and their development is not affected. These findings are really used to prompt diagnostic testing. There's a few common soft markers that come up often enough that it may be helpful to know what they are. For example, there is an ecogenic intracardiac focus. That's a small bright spot in the heart. This almost always disappears on its own and has no impact on heart function. Another common one is a co-roid plexus cyst. This is a small fluid filled space in part of the brain that produces spinal fluid. Again, this typically resolves before birth. There's also shortened

43:36long bones that refers to an ultrasound measurement of an arm or leg bone that's on the smaller side for gestational age, but most babies with this finding go on to grow and develop completely normally. So if a soft marker comes up, first do not panic. If you have not had a self-free DNA test, then I would have that conversation with your doctor midwife about whether or not it makes sense to do that. If a marker from an ultrasound is paired with another finding like a likely result on a self-free DNA test, then your care provider may recommend a more detailed evaluation. I know we've covered a lot. This is definitely going to be a longer episode up until now we've been talking about screening tests. If a screening test comes back positive, then your care provider

44:36may offer diagnostic testing. Diagnostic tests can confirm with near certainty whether a specific genetic condition is pregnant. And there are two primary diagnostic tests that are used. This would be a Chorionic Villas sampling and an Amniocentesis. Both involve collecting a sample for analysis and both carry a small risk of miscarriage. There is a third test that's a cordocentesis. This collects a small sample of fetal blood from the umbilical cord. This is much less common. Like screening tests, diagnostic testing is optional. In fact, every prenatal test is technically optional, and you can decline any of them at any point. Diagnostic testing in particular is something that many parents weigh carefully. Part of that is because there is a small associated risk. We'll talk about

45:36that. Also, there are some parents that are comfortable with the uncertainty. Or parents that choose not to pursue a diagnostic test because the information from that test wouldn't change how they would want to proceed. Then you have parents who want a definitive answer. They want to know what's going on with their baby so that they can plan ahead. This is a personal decision. There is no wrong choice. If you have a positive screen test and a diagnostic test is offered, this is a choice. It's not something that you have to do. A Chorionic Villas sampling. This is usually abbreviated CVS. This can detect chromosomal abnormalities and genetic disorders. The window for this is pretty short. It's between 10 to 13 weeks of pregnancy. This involves collecting a small sample of placental tissue from where the placenta attaches to the uterine wall. There's two approaches to

46:40this procedure. First is trans cervical and this is where an ultrasound guides a thin catheter through the cervix to the placenta and then sections out cells. The other approach is a trans abdominal approach and this uses an ultrasound to guide a long thin needle through the abdomen. The actual sample collection takes just a few minutes and the whole procedure from start to finish you're looking at about 30 minutes and then results are typically available in five to seven days. Accuracy for detecting chromosomal abnormalities is very high, around 98 to 99%. But like all diagnostic tests, a CVS can't predict the severity of a condition. It can only tell you whether or not it is present. The primary risk of this test is miscarriage and studies show that miscarriage

47:40rates are between 0.2 to 0.3% with an amniocentesis. One thing that's really important to know if you will have an amniocentesis is that the experience of the provider that's performing the test and how frequently this test is performed at the facility where you're doing it both have significant influence on the risk level. In a large national registry study from Denmark, they analyzed over 64,000 procedures. And what they found was that departments that performed fewer than 1,500 procedures over 11 years, this was a pretty long term study, had higher miscarriage rates. Centers that did much more higher volume of this test tended to have lower complication rates. So if you are considering a CVS or an amniocentesis, which we'll talk about in a minute,

48:43it's reasonable to ask how experienced your provider is with this procedure, how often they do it, or ask how many of these procedures are performed weekly, monthly, annually to determine whether this is something that is done routinely at the facility where you're doing it. In addition to that very small miscarriage risk, other possible side effects include spotting, cramping, and pain at the puncture site. There's very rare complications. If you have a CVS and you develop fever, chills, if you're leaking amniotic fluid, those are signs that you would want to contact your care provider right away. And remember, these complications are very rare. Then you have an amniocentesis or an amnio. This happens later in pregnancy than a CVS, typically between 15 to 20 weeks. And for this, your provider uses an ultrasound to insert a thin needle

49:44through your abdomen into the amniotic sac, and then it collects a small sample of amniotic fluid. That contains cells shed by your baby. So it can reveal chromosomal abnormalities, genetic disorders, and neural tube defects. The actual fluid collection takes less than five minutes, but the full procedure from start to finish is about 45 minutes. Then results can take anywhere from a few days to a couple of weeks depending on what your provider is testing for. Accuracy for detecting chromosomal abnormalities is greater than 99%. One advantage of an amnio over a CVS is that it can also screen for neural tube defects. And specifically, it's looking to measure alpha-fetoprotein cells in the amniotic fluid. As with a CVS, the primary risk is miscarriage.

50:45Research estimates that risk at about 0.3%. In addition, remember that risk will be lower at a center that performs this procedure more regularly. Other potential side effects very similar to a CVS, pain or cramping or irritation around the puncture site, and then rarely women experience fever, chills, heavy cramping, leaking fluid. Those could be signs of an infection or complications that you would definitely want to call your care provider about right away. Then you have cordocentesis. This is much less common. It uses an ultrasound to guide a thin needle into the umbilical cord and collects a sample of fetal blood. And this is a procedure that's usually reserved for very specific situations when an amniocentesis, a CVS or ultrasound have not

51:47produced a clear answer. This is typically done after 17 weeks. Primary risk again is miscarriage, but it does have a higher miscarriage rate at about 1.3%. One thing that I'd like to just touch very briefly is paternity testing during pregnancy. A lot of people may not need this, but if this is something that you were interested in, it is an option. Cell-free DNA can confirm paternity. There's also a non-invasive prenatal paternity test that uses the same technology as a cell-free DNA test, and that requires a blood draw from you and then a sample from the potential father. And this is something that can be done early on at about eight weeks of pregnancy. It's highly accurate. There's reliability above 99%. As you can see, there's a lot of tests

52:49available, and this can all feel very confusing and overwhelming. In some cases, you may consider meeting with a genetic counselor. This is a trained professional that specializes in translating genetic information into practical understanding. Meaning with them can be really helpful in some specific situations. If you have a family history of a genetic condition, you may want to talk to a genetic counselor. They can also help you if you got a positive screening result to help you understand what that test means and what your diagnostic testing options are. Or if you're considering expanded carrier screening or navigating pre-implantation genetic testing as part of IVF. If you are over the age of 35, your provider may bring up genetic counseling as an option. If you're getting to your mid-30s or you're past that mark, please do not panic. There is an

53:53episode that has a full deep dive into how age affects your pregnancy. Don't panic. Go listen to that episode. Pregnancy at age 35 and older is becoming increasingly common. And we've come a long way from labeling those as geriatric pregnancies. Most pregnancies in this age range over the age of 35 proceed completely normally with healthy babies and no complications. If you talk to a genetic counselor, they can help you understand what a test tells you, what it doesn't tell you. They can walk you through probabilities and implications, all in very plain language. They can also help you think through decisions that you may need to make regarding planning for potential care or pursuing diagnostic testing. If you would like to meet with a genetic counselor, and this is not something that has been explicitly offered by your care provider, this is definitely something that you can request. Most of this episode has focused on

54:59what these tests are. And I know that it's pretty technical. From here, let's talk about how to approach these as a patient. So this involves knowing your options, your costs, planning ahead, and everything else that goes into making testing decisions. One of the most important things to understand about any prenatal test is that every test should come with informed consent. That means that your provider explains what the test is, why they're offering it, what the results can and cannot tell you, whether there are any risks, if there are any alternatives, and you always have the right to decline any test. When procedures become routine, as much of this testing has, it doesn't always feel like you have a choice, but you do. Providers, doctors, midwives, hospitals, they all have their own policies, procedures, routine protocols, and testing is often

56:04wrapped up in those routines. So you can find yourself kind of getting put on a track. They're going to tell you what they want to do, or they'll just tell you, hey, today this is what we're going to do in this appointment, we're going to take this test. And a lot of parents are very comfortable going along with that. And if that's the case for you, then fantastic. That makes your job very easy. But just because something is routine does not mean that you do not have a choice in it. You always have a choice. The next tip is to plan ahead. If you show up to an appointment, and your doctor says we're taking this test today, it doesn't feel like you have a lot of choices because you're getting put on the spot. You know that you have limited time available for your appointment. But if you know ahead of time that a test is coming up and you have time to educate yourself, then you can talk through it with your partner. You can make a decision way in advance as to whether you want to opt in, opt out, or have a more in-depth conversation with your doctor,

57:10midwife. That's going to make you much more prepared and a much more active participant in your prenatal care. One way to do this is to ask ahead of time what tests are coming up. So at the end of every prenatal visit, I would just briefly ask what can I expect to happen at the next appointment. Another really simple way to do this is to follow your pregnancy week by week. The 40 weeks podcast has a short episode for every week of pregnancy. These are only six minutes long and it will cover what's going on with you, what's up with your baby, and what to expect at upcoming appointments. That makes it very easy to stay on top of what's coming next. You can check that out anywhere that you listen to podcasts. Another thing I would like you to consider is including your partner. Of course, the decisions that you make about prenatal testing are ultimately yours, but it's a lot easier to navigate this when you're not doing it

58:14alone. So I recommend first that your partner attend your prenatal appointments with you. That gives them the best information to help you think through options. They may be asking questions that you haven't thought of. They can help advocate for you. If you have questions or concerns about particular tests or procedures, if your partner cannot be at your appointments in person, even having them via a phone call or a video call can be helpful. Two situations in which partners often get directly involved. One is carrier screening. So if you come up positive for a specific result, it's likely there will be a discussion about also testing the baby's father. The other is the anatomy scan. If your partner can't go to every prenatal appointment, and I know that that's not standard, most partners are not going to every appointment, they should be at the anatomy scan ultrasound. The reason for that is that one, it's really amazing to see your baby on an ultrasound,

59:22but also findings may come up in real time during that appointment. If you're in a position where you're getting back unfavorable or unexpected results, that can be very stressful to do by yourself. And having your partner with you means that you have somebody there to help support you. Another thing to keep in mind, before you take any test, ask your care provider when you can expect results and how you will receive those results. Many providers will only contact patients for abnormal results. So if you don't hear anything, it often means that everything is normal. But it can be really difficult to be waiting for a test result if you have anxiety about it. So if you're not hearing back from your care provider, you always have the option to follow up with them and ask them about the results. If you do get a result that is confusing or that you do not

1:00:24completely understand, ask for an explanation. Some tests return as positive or negative, others give a probability or a risk score. A few like cell-free DNA for micro-deletions require very careful interpretation. So if you get a positive screening result, the next step is usually a conversation about diagnostic testing, genetic counseling. But interpreting these results can be very confusing. And remember that a positive screening test only indicates that you may want to consider further testing. It does not diagnose anything. The single most important thing that you can do with everything that we've talked about today is talk to your doctor, midwife. They know your medical history. They can interpret results in the context of your pregnancy. Do not be intimidated to speak up and ensure that your

1:01:25questions and the topics that are important to you get addressed. Your doctor, midwife is your trusted partner and navigating your prenatal care. And the more clear and open conversations you can have with them, the more confident you will feel in your decisions. Prenatal testing is a very powerful set of tools. This is something that our parents really didn't have available. But it also carries real emotional weight. So if you feel anxious going through any or all of these tests, understand that that is completely normal. And I don't want you to feel like you need to understand every specific detail about all of these tests ahead of time. This episode should give you a really great baseline of information for all the prenatal tests in the first half of your pregnancy so that you can have a productive conversation with your doctor, midwife and land on the choices that feel right for you. Today's episode covered

1:02:27prenatal testing in the first half of pregnancy. I know this episode ran very long. You can see why this has to be continued in a separate episode. And in a subsequent episode, we will talk about testing in the second half of your pregnancy. To recap today's episode, we talked about all of the prenatal tests that could come up in the first half of your pregnancy. We talked about urine analysis, blood tests and panels, cell-free DNA, genetic testing. We talked about diagnostic testing, like a CVS, amniocentesis, cortocentesis, touched on paternity testing, went through what you can learn by talking to a genetic counselor. And then wrapped up with everything you need to know about navigating your options. The importance of informed consent, planning ahead, involving your partner and how to interpret results.

1:03:28Thank you for tuning into the pregnancy podcast today. I hope that you find this episode helpful. Please share the pregnancy podcast if you have a friend that's expecting. So many listeners discover this podcast through recommendations and I appreciate your sharing. As always, you can reach me the nessa at pregnancypodcast.com. You can read the full article and see all of the resources that accompany this episode at pregnancypodcast.com slash prenatal testing. You just heard a lot of information about prenatal testing. And there's a companion episode coming up next that will cover the second half of pregnancy. Both of these episodes plus hundreds more require a ton of research. And I really enjoy doing all of the hard work so that you don't have to.

1:04:29Become a pregnancy podcast premium member and you get access to every single episode of the podcast. And it's all add free. There are hundreds of episodes exclusively available to premium members with evidence based information. You won't find anywhere else. Check it out at pregnancypodcast.com slash premium.