Ep 257: Everything You Need To Know About The Prenatal Tests You’ll Get During Pregnancy

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In this episode, you're going to learn all the tests that are recommended during pregnancy. I’ll break things down by trimester and talk about why the tests are done and what the results of the tests mean. You can use this information to prepare for upcoming tests or go back and ask questions about ones that were done in the past.

The bulk of testing is done in the first trimester. Early screening is vital for the health of you and your baby. Healthcare doesn’t often focus on preventative care so use this opportunity to be proactive and plan ahead.

In this Episode, You’ll Learn About:

  • Which tests are recommended and done during pregnancy
  • Why you should register for access to your electronic medical records
  • Why we don’t want you to go into birth having low platelets
  • What happens in the case of an RH negative parent and an RH positive baby
  • Which conditions can be passed on from parent to baby
  • Why we screen for several STIs
  • What we can learn from analyzing a urine sample
  • Why genetic testing is done
  • What an anatomy scan looks for
  • Why it’s important to check for and address gestational diabetes

Links Mentioned in the Episode

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Dr. Nicole (00:00): Do you know what tests are done during pregnancy and perhaps more importantly, why those tests are done and what the results mean? Well, you will after listening to this episode,

(00:17): Welcome to the All about pregnancy and birth podcast. If you're having a baby in the hospital, you are giving birth in a system that too often takes away power from women over what happens in their own bodies. I'm Dr. Nicole Calloway Rankins, a practicing board certified OBGYN, who's had the privilege of helping well over a thousand babies into this world. I've been a doctor for over 20 years and I'm here to help you take back your power, advocate for yourself and have the beautiful pregnancy and birth that you deserve. This podcast is for educational purposes only and it's not a substitute for medical advice. Check out the full disclaimer at drnicolerankins.com/disclaimer. Now let's get to it. Hello there. Welcome to another episode of the podcast. This is episode number 257. Whether this is your first time listening or you have listened before, I'm so glad you're spending some time with me today.

(01:12): So in this episode, you are going to learn all of the tests that are recommended and done during pregnancy. I will break things down for you by trimester and you'll learn why the tests are done and what the results of the test mean. You can use this information to know what to expect as you go through your pregnancy or also to go back and ask questions about tests that were done in the past. I have to say we're not always that great about sharing the results of the test even if they are normal. So this just may be something that you want to look into. Now, don't worry about writing anything down. I have put everything together and a free guide. You can download it@drnicolerankins.com slash prenatal. It contains all of the tests including a handy one page sheet of everything that's done and then more additional explanations as well.

(02:10): Now before we get into the episode, let's do a listener shout out. This is from MK 0 0 0 0 and the title of the review says Second time mom learning a lot. This podcast is packed full of useful information even as a second time mom, I'm learning a lot. This will be my first hospital birth, so it's helpful that the content is from the perspective of a hospital-based OB GYN, the tone is personable while still being very fact-based. For example, Dr. Calloway Rankins does a great job at distinguishing when she is sharing her opinion versus sharing an ACOG statement. She also does a great job educating listeners on the handful of things that can happen during labor and birth that qualify as true obstetric emergencies. Well, thank you so much for that lovely review. I really, really appreciate it and I'm so glad that as a second time mom, you are finding this podcast helpful. All right, now let's get into talking about prenatal test.

(03:14): One thing I want to say about prenatal test and really all tests that you get these days, most health systems have some sort of electronic medical record where you can access your lab results. I highly, highly suggest that you register for any type of electronic medical record system where you can access your lab results. One, you'll be able to look at information whenever you want and it's your own information and you should be able to look at it, but also it can come in handy if you go between different places. For example, you by some chance end up at another hospital for some reason or something along those lines. You can access information. Sometimes it can be even as detailed as notes included in the computer, the app program, and that can be very, very helpful. So do for sure register for any sort of electronic medical profiles that you have.

(04:10): And these days, actually by law, you are entitled to get or you will get the results of the test almost immediately. Sometimes it will be before your doctor has a chance to review them. So I will say that yes, register for these, but be mindful that if the results come back and there are some concerns, give your doctor some time to respond. They cannot respond to things right away. Sometimes lab test results may pop up in the electronic medical record at midnight or weird times whenever the labs run those results. Don't call your doctor in the middle of the night to talk about those test results. Just wait until the next day. So give them a little bit of time to see the results they can't address or respond to results that come back immediately. Okay, so let's get into the test. The first one is the initial visit.

(04:58): You're going to get a lot of tests done at your initial or first prenatal visit, and I'm just going through them in no particular order. Just these are the tests that are done. One is a complete blood count that's called a CBC, and a complete blood count counts the number of different types of blood cells in your blood. We focused mostly on red blood cells, white blood cells, hemoglobin, hematocrit and platelets. Red blood cells carry oxygen from the lungs or oxygenated blood from the lungs to the body. Red blood cells are what carry oxygen in our body. White blood cells fight infection and disease when they're elevated. That can be a sign that there's infection going on. Hemoglobin is the actual oxygen carrying protein that is in red blood cells and then hematocrit is the percentage of red blood cells in the blood. Those two numbers are related.

(05:56): Hematocrit is roughly three times hemoglobin and then platelets help your blood clot to stop bleeding. The things we get concerned about especially are low red blood cells. That's anemia, so that's going to be reflected with a low hemoglobin or a low hematocrit. In that case, you will be prescribed iron to help bring your blood count numbers up and then platelets can show if you have some issues with blood clotting. There are some conditions that can develop during pregnancy or a condition called ITP where you have low platelets and pregnancy or gestational. Thrombocytopenia is another one where you have low platelets in pregnancy. Typically that doesn't show up until later in pregnancy, but it is something that we like to keep an eye on because there are some things we can do to increase your platelet numbers before you get to birth. We don't want you to go into your birth having very low platelets because that's going to increase your chances of bleeding.

(06:57): Next up is blood type. This test for whether you have type OAB or AB blood and your blood type is determined by the presence of certain antigens. Antigens are protein molecules on red blood cells and those antigens can trigger an immune response if they are foreign to the body. So if you have type O blood, you don't have any antigens on your red blood cells. If you have the antigen on your red blood cells B, you have the B antigen, A B blood, you have both A and B antigen, and the way that comes into play is during transfusions. So if you have type O blood, you can only receive type O blood because if you have type O blood and you receive a transfusion with a blood, if the person with type O is going to recognize that a antigen is foreign as attack and attack it, so the person with O blood cannot receive A B or ab B blood.

(08:03): On the flip side, the person with AB B blood can receive blood from anybody. So they have the A antigen, the B antigen, so if they get B blood that has that B antigen, their body won't recognize it as foreign A blood. Same thing. O has no antigen so everybody can receive O blood. So that's the difference between OAB and A blood. We also look at the blood test to determine whether or not you have the RH factor. RH is a protein that can be present on the surface of red blood cells. Most people have the RH factor and are thus RH positive. If you don't have the RH factor, then you are RH negative. So the combination of the two results in giving us the eight most common blood types, A positive A negative B, positive B negative O positive O negative, AB positive and AB negative.

(08:59): So the presence of the AB or AB antigen, and then whether or not you have rh, there are some other blood antigens that we look for that are more rare, but in general your blood type is going to fall into one of those big categories first. Now, if you're RH negative, this can cause problems in future pregnancies because if your RH negative and your partner is RH positive, if the baby is RH positive, there's a possibility that your baby's RH positive blood cells can get in your bloodstream and you are RH negative. That's most likely to happen around delivery or birth. And if those RH negative, I'm sorry, RH positive blood cells get into your RH negative bloodstream, your body is going to recognize those as foreign and attack them. It's going to create something called antibodies that will attack that RH positive cells. So what happens is in a future pregnancy, if you have another baby who is RH positive, then your immune system is already revved up and ready to attack anything that is RH positive and it's going to attack that next pregnancy that baby's RH positive blood cells.

(10:18): It can cause severe anemia and it can be quite catastrophic actually. So in order to prevent that, we give you something called RhoGAM during pregnancy if you are RH negative. And what that does is RhoGAM essentially binds up any RH positive cells very quickly before your blood system can recognize it and then attack it. So RhoGAM is given generally twice, once towards the end of pregnancy in the third trimester and that carries you through to birth because that's going to be the most likely time that the mixing of mom and baby's bloods happen and then after birth as well. We also give it any anytime there's bleeding during pregnancy because that can also increase the chances of mom and baby's blood mixing. Okay, hope that makes sense. Next up, we have rubella. Rubella is also known as German measles. German measles can actually make a baby very, very sick if mom is infected during pregnancy and what the blood test checks for.

(11:22): It checks for whether you've been exposed to rubella before, either through infection or the vaccine. We can't tell the difference. We just can tell that you've been exposed to it before. The vast majority of people are vaccinated against rubella and childhood. It is part of the MMR vaccine series, so measles, mumps, and rubella. Now if for some reason you have not been exposed to the rubella vaccine or the vaccine was ineffective, then you will be what's called rubella non-immune and you should definitely receive the vaccine after pregnancy. You don't get the vaccine during pregnancy because it is a live virus vaccine and we do not do any live virus vaccines during pregnancy because it increases the chance of actually getting the infection from the vaccine. Alright, so that's rubella, and then next up is hepatitis. We check for hepatitis B, we also check for hepatitis C.

(12:24): This is a blood test. Hepatitis B and C are both infections of the liver, and when you have hepatitis B or C, you can potentially pass it on to your baby. Now most folks or many are vaccinated against hepatitis B because it is a childhood vaccine series in the last few decades. So most people are vaccinated against hepatitis B. There is no hepatitis C vaccine available. However, if there is concern that mom has hepatitis B or C, then there are some things that can be done for the baby when the baby is born in order to reduce the chances of the baby having a severe hepatitis infection. So we check these numbers so that we can prepare for it and make sure the baby has the best options available to not get hepatitis after birth. We'll also want to monitor any issues with mom's liver function during the pregnancy as well.

(13:25): We also check for HIV, human immunodeficiency virus. All pregnant women are screened for that. That's with a blood test. And the reason we screen for that is because if a woman is pregnant with HIV, then she can definitely pass it on to her baby. However, there are medications that are available that will greatly, greatly reduce the chances of passing HIV onto a baby. This is one of the really modern miracles of medicine. The medicines that have been developed to treat HIV, we can definitely get the viral numbers to levels that are essentially undetectable. Women with HIV can still have a vaginal birth, so we screen for HIV because there are very good treatments available for it. We also check for sexually transmitted infections. The main infections that we check for are syphilis, gonorrhea, and chlamydia. Now all pregnant women are screened for syphilis. That is generally mandated by law that all pregnant women are screened for syphilis.

(14:27): It's done by a blood test. And the reason that we check for syphilis is because syphilis infection, congenital syphilis where a baby gets syphilis from mom can be very devastating and unfortunately, the number of babies born with congenital syphilis in the United States has increased over the past decade. In 2012, that number was 334, and in 2022 it was up to 3,761. So that is a very big increase, a 1000% increase since 2012 and just a huge increase. Nearly 300 of the babies in 2022 who were infected with congenital syphilis, 300 of those 3,761 either died or were still born. According to data from the CBC. These are some of the highest numbers reported in the US in more than 30 years. And congenital syphilis is considered a never event, meaning it's an outcome that should never happen because it is always preventable or nearly always preventable as long as it is caught and treated in time.

(15:51): So as long as we catch syphilis during pregnancy, then mom can be treated with penicillin. It's an IV penicillin and it's given in a few week doses or I am in the muscle penicillin and as long as it's treated, then the congenital syphilis won't happen. So really anybody who's getting prenatal care, we shouldn't miss syphilis. So that's why we test for it. There's been this huge increase. And then for gonorrhea and chlamydia, the reason we get concerned about gonorrhea chlamydia is primarily actually around delivery. It can maybe increase the chances of preterm labor and preterm birth, but the biggest issue is around birth and infection in the baby's eyes. So most of us check everyone for gonorrhea and chlamydia and that can either be done through a vaginal swab or it can be done through a urine sample. In that case, it's actually detecting DNA fragments of the gonorrhea or chlamydia virus that, or sorry, bacteria that are hanging around in the urine.

(16:59): And if these tests are positive, they're easily treated, partners need to be treated and then we retest later to make sure the treatment has worked alright. Also, we check in the initial visit. It's a lot that happens at the initial visit. We do a lot of tests at the initial visit, not so much going forward. The next thing is a urinalysis. And a urinalysis is an analysis of urine and it looks for signs of infection in your urine. So it looks for red blood cells, white blood cells, bacteria. It also looks for glucose or sugar in your urine, which could be a sign of diabetes. And we also measure protein in the urine. Increased levels of protein in the urine may be a sign of preeclampsia. Now, if we see protein in the urine at an initial visit and the blood pressure's, that's just something that we're going to keep an eye on.

(17:52): Protein in the urine by itself is not an indication of preeclampsia. It's one of the things that we look at in the constellation of pictures. Also, preeclampsia typically doesn't happen until the third trimester of pregnancy. Many doctors do a urinalysis at every prenatal visit to look for that protein, to look for glucose. So I would say most even do that, but you're definitely going to have one at that initial visit. We're also going to do a urine culture, a urine culture test, your urine for bacteria, and if the bacteria is in high enough levels, that means there is a urinary tract infection. Now, asymptomatic bacteria which is bacteria in the urine and you don't know it so you have high levels of bacteria in your urine and you don't know it. That's actually more common in pregnancy. We don't necessarily completely understand why we think it may be some of the physiologic changes that happen in the body during pregnancy. And the reason that we want to catch that is because bacteria and the urine and a UTI can increase the chances of preterm labor and preterm birth. So we're going to check and make sure there's no evidence of infection that you're not feeling and treat that and make sure we take care of that to decrease those chances of that preterm birth.

(19:12): Okay, last two things we do at that initial visit, or I would say in the first trimester, it may not exactly happen at that initial visit, is an ultrasound. You're going to have an ultrasound in that first trimester in order to establish your due date. An ultrasound done in the first trimester is the most accurate at determining due date. I do have another episode on due date, episode 1 47 of the podcast. You can check it out@drnicolerankins.com slash episode 1 4 7. But in general, ultrasound done the earliest ultrasound is going to be the most accurate at determining due date. We compare it with the due date estimate based on your last menstrual period, and if they're within seven days of each other, then we use your last menstrual period date. If they are not within seven days of each other, then we go by the ultrasound date.

(20:02): One thing that people get confused about with due date is that you may have a later ultrasound that shows a different due date. That does not mean that your due date changes. That means that that later ultrasound is coming up with a different estimate of your due date. But later on in pregnancy estimates of due date are less accurate. The further along you get the less accurate the ultrasound is the estimating due date. So we don't change your due date based on the later ultrasound. We always keep your due date based on that first ultrasound you had. It does not change. Now we are also in that first trimester ultrasound increasingly doing detailed anatomy ultrasounds in the first trimester. Our technology is getting better that we're able to see more structures in the baby in the first trimester. And honestly, part of the reason that we're doing that is because of restrictions on abortion in the United States and giving people the opportunity to know earlier whether or not there are any serious problems or issues going on that we can see with ultrasound to give people the opportunity to end a pregnancy if they so choose earlier because abortion restrictions are getting more and more intense in the us.

(21:11): And last thing we do is genetic screening. Most folks these days have nipped non-invasive prenatal testing in the first trimester. Some people refer to it as a gender test, but that is actually not the only thing that it's for. It takes a sample of your blood, analyzes something called cell-free DNA, and it tests for the three most common chromosome disorders, trisomy 21, which is an extra chromosome 21, that's down syndrome. Trisomy 18, which is an extra chromosome 18 and trisomy 13, extra chromosome 13. And as I said, it can also tell you the sex of your baby. It does not test for all chromosome problems. It also does not test for any structural problems like heart defects. And it is a screening test, meaning positive results do suggest a disorder is present, but they cannot tell you that with 100% certainty. If the disorder is truly there, it may be a false positive result.

(22:12): So in order to know for sure, generally testing like amniocentesis is required to definitively diagnose a chromosome problem and amniocentesis is going to be a little bit better than something called CVS, which is choic villa sampling because sometimes the placenta, which is what choic villa sampling samples, it's a little piece of the placenta. There can be a genetic mosaicism in the placenta. That's a fancy way of saying that the genetics and the placenta may be a little bit mixed up for lack of a better way to put it. But amniocentesis is definitive because it's going to be only the baby's blood cells. So that's going to give you that definitive answer, but most people in that first trimester are going to have the nipped test. If you want to know more about genetic testing, I have a fantastic episode with a genetic counselor. That's episode 1 46 of the podcast, dr nicole rankins.com/episode 1 4 6.

(23:07): Now the last thing that you may get at that initial visit or sometime in that first trimester is diabetes screening. This is not gestational diabetes screening. Gestational diabetes screening is defined as diabetes that develops in the third trimester. This diabetes screening is really looking for undiagnosed or undetected diabetes or intolerance or difficulty processing blood sugar that was present before pregnancy, but that we just hadn't picked up yet because maybe you hadn't seen your primary care doctor in a while, maybe it hadn't been tested. So this is really to pick up people who probably had issues with processing glucose before pregnancy. Some people who are at higher risk of that are if you carry extra weight. So if your body mass index is 30 or more, we're generally going to do a diabetes screening early in pregnancy. If you have high blood pressure, that increases the chances that you also had diabetes that was unrecognized or difficulty processing blood sugar.

(24:04): Those with PCOS also, if we see sugar in the urine, that can be a sign of having diabetes that was present actually before pregnancy. We're just picking it up in the early part of pregnancy. Okay, so that's it for all those first trimester tests. Those are the ones that's where you're going to get the most things done. The rest of the pregnancy, there are just a few tests that happen in the second trimester and that's between 14 and 28 weeks. The big thing you're going to get is that anatomy ultrasound, sometimes it's called a level two ultrasound, typically done around 20 weeks, can be done anywhere from 18 to 22 weeks. This is the ultrasound where we get comprehensive views of your baby from many angles. So it typically takes a while, 30 to 45 minutes. We look at the measurements of how your baby's growing, how much your baby weighs.

(24:55): We look at the face, we look at the mouth, we look at the brain, we look at the spine, heart, stomach, bladder, kidneys, the sex organs, limbs, the placenta amniotic fluid. So a very comprehensive look. You may get 3D images if the ultrasound machine being used has that capability. Not all offices have those 3D image machines, but a lot of them do. And anatomy ultrasound is very good at seeing potential problems very good, but it does not detect all possible problems that can occur. It detects a lot of things but does not detect all of the possible issues that can occur. There are some genetic screening blood tests that used to be done around this gestational age, but quite frankly, those aren't really done much anymore since people are mostly getting that first trimester NIPT screening. The other thing that happens in the second trimester is gestational diabetes screening. This test is going to be done between 24 and 28 weeks to screen for gestational diabetes. That's a specific type of diabetes that develops later in pregnancy.

(25:59): When you have gestational diabetes, you didn't have diabetes before pregnancy and for this test, you drink a sweetened liquid that has 50 grams of glucose. We then measure your blood sugar 60 minutes after you finish the drink despite what people say, you do not need to fast before the test. You don't need to change your diet before the test. You actually don't want to try and game the test at all if you have gestational diabetes and you want to know so it can be treated appropriately. So go on about your usual business. You don't have to fast take the test, drink the sweet drink. I think it's disgusting. The orange one to me is the best flavor, but there's also cola. There are also some different options, like fresh test is an option that's different than the gluc that also works in order to do gestational diabetes screening.

(26:55): And if the results are abnormal, this is a screening test, then you need to have another test to decide for sure. If you have gestational diabetes, that's a three hour test for that one. You do have to be fasting and you drink something and then we check your fasting blood sugar, your one hour, two hour and three hour blood sugars. And if two of those are abnormal, then that is definitively gestational diabetes. Now, there are some instances if on the screening test, your blood sugar is really high on the screening test. We don't have to do the three hour test because it's so high that it qualifies as having gestational diabetes. But in general, it's a two-step process to diagnose it for sure. The other thing that we do is we repeat your blood cell count to see if you're anemic. We want to definitely have that number up and we check it again in the second trimester so we're closer to delivery and we have some time for you to take iron to get your blood count up.

(27:53): You definitely don't want to go into your birth with a low blood count level because if you have any issues with bleeding during your birth, then that's going to make things worse if you're already starting off with a low blood count. So we check your blood count again at that third trimester to give it some time to build back up prior to birth. Okay, let's finish up with the third trimester. There are only a couple of tests that are done in the third trimester that's greater than 28 weeks. One is GBS, that is group B strep or group B streptococcus that bacteria. GBS is a common bacteria that somewhere from 15 to 40% of pregnant women carry and the bacteria does not cause any concern outside of pregnancy. However, when you are pregnant, this bacteria could hurt your baby in rare circumstances during labor and childbirth.

(28:43): Group B strep and a baby can be pretty severe. It doesn't happen very commonly, but if it does happen, it can be dangerous. So we test for GBS between 35 and 37 weeks of pregnancy with a vaginal and rectal swab. This is a swab that your doctor does or they may offer you the option to do the swab yourself. I do have a podcast episode on GBS, but it's been a while, probably three years, maybe longer than that. So I am going to update that episode. So stay tuned for an updated episode on GBS coming in the near future. And then the other thing that we do in the third trimester is repeat that syphilis screening again, because again, syphilis is on the rise in the US and this is something that is completely preventable. So we repeat that syphilis screening in the third trimester.

(29:34): Again, just to be sure. Along with that, we often repeat gonorrhea and chlamydia as well. So to summarize, in the first trimester that initial blood work is the complete blood count, your blood type, hepatitis B and C, rubella, gonorrhea, chlamydia, and syphilis, a urinalysis and urine culture. You're also going to get that early ultrasound and IPT or NIP testing for genetic screening. And you may also get diabetes testing if you meet some or if you have some risk factors in the second trimester, you'll get that anatomy ultrasound, that's that detailed ultrasound. You'll also get screened for gestational diabetes, and then in the third trimester you'll get screened for group beta strep and syphilis. Remember, you can get all of this information in the handy guide that I created for you. It's dr nicole rankins.com/prenatal. Okay, so there you have it. Please share this podcast with a friend. I want admission to reach and serve as many pregnant people as possible, and I would love your help in doing so. Also, subscribe to the podcast wherever you're listening to me right now, and do leave me a review in Apple Podcast. I'll read those reviews. I love to hear what you think about the show and I can give you a shout out on a future episode. So that's it for this episode. Do come on back next week and remember that you deserve a beautiful pregnancy and birth.