Ep 46: A Guide to Prenatal Testing and What to Expect from Tests in Each Trimester

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Have you ever felt confused about prenatal testing and why your doctor is running so many tests on you during your pregnancy?

I realized that a lot of OBGYNs don't do a great job of explaining all of the tests we do during pregnancy, so I thought I'd walk you through the recommended ones. Thank you to Julie, who suggested this topic in the All About Pregnancy & Birth Facebook Group!

You'll have most of your testing done at the initial appointment, which includes a full blood count and some tests for various infections, too. Then we'll talk about some of the tests you can expect to receive in the second and third trimesters and why we do each test that we do. 

And don't worry about taking notes today - you can download a companion guide to this episode, with all the information about prenatal testing we'll cover today, right here.

In this Episode, You’ll Learn About:

  • What tests you can expect to get at your initial appointment and throughout the first, second, and third trimesters.
  • Why we do each test and how it helps your doctor monitor your health and the health of your baby.
  • A brief overview of some genetic tests you can receive.
  • Why and how we test for gestational diabetes, which is fairly common in the third trimester.
  • Why many doctors don't do an ultrasound in the third trimester.
  • Some of the infections that doctors test for and how they can affect your pregnancy & birth.

Links Mentioned in the Episode

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Speaker 1: Have you ever gotten confused about all of the tests that are done during pregnancy? Well, this episode is for you.

Speaker 2: Welcome to the All About Pregnancy & Birth podcast. I'm your host, Dr. Nicole Calloway Rankins, a board certified Ob Gyn physician, certified integrative health coach and creator of The Birth Preparation Course, an online childbirth education class that will leave you feeling knowledgeable, prepared, confident, and empowered going into your birth. Quick note, this podcast is for educational purposes only and it's not a substitute for medical advice. You can see the full disclaimer at www.ncrcoaching.com/disclaimer.

Speaker 1: Hey, Hey. Hey. Welcome to another episode of the podcast. This is episode number 46. I hope you are having a great day today. I'm having a great day because you are here with me. So today's episode of the podcast was inspired by Julie. Julie is a member of my Facebook group, All About Pregnancy & Birth. And Julie asked if I had a resource about what to expect regarding tests done during prenatal visits and I thought, hmm, that would be a great episode for the podcast. So here we are. Now I know this is not something that we as OB GYN's often do a good job of explaining. I think oftentimes it ends up being, hey, it's time to get some bloodwork, here's the slip to go to the lab without a good explanation of what tests are being done and then there's often a lack of followup about the results afterwards other than "hey, everything was okay."

Speaker 1: I know I was probably guilty of doing that myself when I was in office practice. So what I'm going to do in today's episode is go over all the tests that are recommended during pregnancy. I will break things down by trimester. I'll talk about why the tests are done and what the results of the tests mean. So you can use the information in this episode to know what to expect going forward or also you can use it to go back and ask questions about tests that were done in the past. Now, do not worry about writing anything down from the episode. I have put everything together in an awesome free guide that you can download at www.ncrcoaching.com/prenatal. It summarizes everything that I'm going to talk about today and I will link to that guide in the show notes. Again, that's www.ncrcoaching.com/prenatal.

: Now I mentioned that this idea came from a member of my free Facebook group, All About Pregnancy & Birth. And if you are not a part of that group then you should be. It is a great place to connect with other pregnant mamas and get even information about pregnancy and birth. The community manager of the group is an experienced doula Keisha and of course I am in the group as well. You can search for the group All About Pregnancy and Birth on Facebook or there will be a link to join the group in the show notes. Now another thing of course you need to check out is my free online class on how to make a birth plan. This gives you the information that you need in order to make a birth plan that works to help you have the birth you want. I talk about tips to get your doctors and nurses to pay attention, eight key questions you need to ask, how to approach making your birth wishes, what to include, all of that good, great stuff. The class is offered multiple times a day. So you can just go to www.ncrcoaching.com/register and sign up for a time that works for you.

: All right, so let's get into today's episode on prenatal tests. So the first time that you're going to get a lot of tests, and actually you'll hear in the episode, it's actually not that many tests that you get during pregnancy, the biggest battery of tests is at that initial prenatal visit. And you're going to get several blood tests. I'm just going to list them out here, and then also a couple of urine tests, and then I'll go back and explain each one in detail. All right, so at that initial visit, you're going to get a complete blood count. You're going to get your blood type, get checked for rubella, hepatitis B, HIV, sexually transmitted infections, and you'll get a urine analysis as well as a urine culture.

Speaker 1: So all of that is going to happen at that first visit. And let me break down what each of those are. Okay, so a CBC or a complete blood count. What that does, it's a blood test and it counts the number of different types of blood cells in your blood. So it counts white blood cells, red blood cells, and something called platelets. A number of low red blood cells is anemia. So if you have anemia, then you may need to take extra iron during your pregnancy, depending on how low the number is. Pregnant women actually have something called a physiologic anemia where it's an adaptation to pregnancy, where you're naturally a little bit anemic, but if it's very severe, you may need to take extra iron. Another thing we look at is the platelets. Platelets are something that help our blood clot, and if you have a low number of platelets, then that gives us a clue as to whether or not you may have some trouble clotting at delivery and that's something that we would need to follow and potentially get evaluated by a specialist if they're super duper low.

: All right. The next thing, and this is in no particular order, I'm just kind of listing them out here. The next thing is your blood type. This is going to test for whether or not you have type O, A, B or AB blood. And we also check to see whether or not you have something called the RH factor or the rhesus factor. RH is a protein that can be present on the surface of red blood cells and most people have this RH factor on the surface of their blood cells, so they are RH positive. If you don't have the RH factor, then you are RH negative. It's not very common. Now the combination of these two results gives us the eight most common types of blood, so A positive, A negative, B positive, B negative, O positive, O negative, AB positive and AB negative.

: And what the O, A, B or AB means is whether or not you have those particular proteins present. So if you have type O blood like I do, I'm O positive, then you do not have A or B present on your red blood cells. If you have type A blood, then you had that A protein present. B, you have the B protein present. AB, you have both proteins present. So that's what we look for in the blood type test. Now regarding the RH factor, if you are RH negative, this can cause problems particularly in future pregnancies. So what happens is if you are RH negative and your partner is RH positive and your baby is RH positive, what happens during your pregnancy and during delivery, especially tiny bits of your baby's blood will get into your bloodstream and you will recognize that RH positive factor as being foreign and your body will attack it. Now usually it doesn't cause an issue for that pregnancy that you're carrying, but what it does is for the next pregnancy and the pregnancy after that, then it's when it can rear its head and really cause some significant damage because your body, if you have another RH positive baby, your body will attack that baby's red blood cells.

Speaker 1: So in order to prevent that from happening, we do something called Rho GAM. And RhoGAM basically finds all those tiny bits of the positive factor in your blood and kind of binds them up. That's a short story explanation of what happens when you're RH negative and why you need RhoGAM. Your doctor can certainly give you a bit of a more detailed explanation, but again, for the blood type, we look for that O, A, B, AB, and whether or not you have the RH factor.

: Okay, so we also test for rubella. Rubella is also known as German Measles. And rubella can make a baby very sick if mom is infected during pregnancy, and what the blood test is, it checks whether or not you have been exposed to rubella before, either through infection or through the vaccine. Most of us are vaccinated against rubella from the MMR vaccine that we got in childhood, the measles, mumps and rubella vaccine. And if you haven't been exposed to rubella or the vaccine was ineffective for some reason, then you may be what's called rubella non-immune or rubella equivocal where you had a little bit of exposure but not enough that your immune system mounted a strong enough response and in that case you're going to get the vaccine after pregnancy. It does not protect you for that pregnancy against rubella. It's going to protect you for your future pregnancies. When you get the vaccine after pregnancy, you cannot get the rubella vaccine during pregnancy. It is what's called a live virus vaccine. So you cannot get that vaccine during pregnancy because you don't want to risk getting a full blown rubella infection.

: We also check for whether or not you are immune to hepatitis B. This again is a blood test. Hepatitis B is an infection of the liver. Hepatitis like HEPA stands for the liver and itis is infections or inflammation. So an infection of the liver and women with hepatitis B can pass that on to their babies. So that's why we check for it. So, we can treat a baby after delivery if need be. Now many, if not most women these days, are vaccinated against hepatitis B because it is now one of the childhood vaccines that's given in the sixth grade ish range. So most folks are protected against hepatitis B or immune to it. But we check for it just in case.

: And then the final blood test that you get is for HIV. All pregnant women are screened for HIV, almost always with a blood test. And if a woman is pregnant with HIV, the reason we screen for is because there's medication that can greatly reduce the chances of passing HIV on to a baby. So that's why we check for HIV during pregnancy.

: All right, now also we check for sexually transmitted infections at that first prenatal visit. All pregnant women are screened for syphilis. That is usually the law, I want to say in all 50 States. I notice the law here in Virginia, but all pregnant women are screened for syphilis just because simple as being passed onto a baby can be very, very detrimental and this is done by a blood test. Many providers also test all women for gonorrhea and chlamydia. That is either done with a vaginal swab or it can be done from a urine sample because it's detected by DNA and some of the DNA fragments can be present in urine if a woman is infected with gonorrhea or chlamydia. Now some providers only test women who are at higher risk. So if you are younger, like under the age of 25 or a teenager when pregnant or if you have multiple sexual partners or if you've had it before in the past, then some providers will use that to determine whether or not someone should be tested. But again, some folks, some doctors, midwives test everybody for it.

: Now if any of those tests are positive, then the infection is treated and then we retest for it later on to make sure that the treatment worked. So syphilis requires multiple rounds of penicillin, whereas gonorrhea and chlamydia require a shot in the muscle to get treated as well as some oral medication. So they're treated pretty easily. Also, most babies in the US get antibiotic eye ointment at birth to help prevent gonorrhea infection, particularly in the eye. So that's another way that we protect against those infections. That's just an aside.

: Okay. Now. Also at that initial visit, I told you is a lot of stuff at the initial visit. We also check for a urine analysis and a urine analysis is just looking at the urine and it looks for signs of infection in the urine like red blood cells, white blood cells, bacteria. It also looks for glucose or sugar rather. That can be a sign of diabetes and it will also measure protein in the urine. Increased levels of protein in the urine may be a sign of preeclampsia. So many doctors do a urinalysis at every prenatal visit, particularly to look for protein as a potential sign of preeclampsia even though preeclampsia doesn't typically present itself until the third trimester. A lot of doctors would do it every single visit and then finally at that initial visit you will get a urine culture. A urine culture specifically sees if your urine grows out bacteria. It's more than just a urinanalysis and if you have bacteria and high enough levels, that means a urinary tract infection. And the reason that we do that routinely is that it's fairly common for pregnant women to have a urinary tract infection and not know it and not have symptoms. So we check for it because having a urinary tract infection can put you at risk for other things, particularly like preterm labor.

Speaker 1: All right, now also in the first trimester, many if not most doctors these days will do an ultrasound in the first trimester in order to accurately establish the due date. An ultrasound done in the first trimester is the most accurate thing that we know or have to determine an estimate of the due date and to learn more about your due date, check out episode 22 of the podcast. I will link to that in the show notes. Due date really is an estimate. It's not like an exact science, and you may also get an ultrasound to evaluate something called nuchal translucency which measures the fluid at the back of your baby's neck. And an increased amount of that fluid is a sign of chromosomal disorders.

: You may also get some genetic testing done. Now, another type of genetic testing that is done in the first trimester is something called non invasive prenatal testing or nipped. And this is fairly new. This takes a sample of your blood and it analyzes something called cell free DNA in order to test for three of the most common chromosomal disorders. So it tests for trisomy 21 which is down syndrome, trisomy 18 and trisomy 13, nipped can also tell you the sex of your baby. It does not test for all possible chromosome issues. Also doesn't test for structural problems like heart defects or anything like that. So you may need additional testing to look for those things where you will have additional testing in the second trimester to have a complete ultrasound. And I'll talk about that in just a second. I'm actually gonna have somebody come on the podcast. One of my good friends, she's been on the podcast before. She's a maternal fetal medicine specialist, and she will talk about all the ins and outs of genetic testing screening.

Speaker 1: I'm not as up to date on genetic testing screening as I once was. So I asked her to come on and give us like an update. So look for that episode to be coming in the near future. Now one more thing that is sometimes done in the first trimester is diabetes screening and that is done if you are at an increased risk of having diabetes. So if you are overweight or obese then you may get diabetes screening as well to check and see if you have diabetes. That's not routinely done. It's offered more for people who are at high risk.

: Okay. So moving on to the second trimester, there are only a couple things that are done in the second trimester. The big thing of course is the anatomy ultrasound and it has various names, anatomy ultrasound, morphology ultrasound, level two ultrasound. You may hear it called different names, but basically this is the ultrasound where we get comprehensive views of your baby from many angles to look at all the structures. It's best done around 20 weeks or so. But anywhere between 18 and 22 weeks is acceptable. And this is where your baby is big enough that everything can be seen, but not too big that you can't get views of the things that you're looking for. So the things that we look at in this ultrasound are measurements of how much the baby weighs. We look at views of the face, the brain, the spine, heart, stomach, bladder, kidneys, the sex, organs, limbs, placenta, amniotic fluids. So we look at those things in very great detail. So that ultrasound takes about 30 to 45 minutes or so.

: Now depending on the type of machine your doctor has or the ultrasound tech has, you may get 3D images as well if the machine has that capability. But not everybody has that 3D capability and 3D is not, I would say it's not really necessary for routine anatomy ultrasounds. I think we're looking more and more into 3D ultrasound to see how it can be helpful in diagnosing things. But really a two dimensional ultrasound is adequate, although I know those 3D pictures are fun. Now the anatomy ultrasound is very good at seeing potential problems, but it does not detect everything. Occasionally things pop up that were not seen on that 20 week ultrasound. Now there's also a genetic screening test that can be done around this time as well to look for chromosomal problems. So if you didn't have it for some reason earlier and you still want it, then there is another option for genetic screening that's done. It's called a quad screen.

: All right, now the other test that's done in the second trimester, and this is later in the second trimester, this is between 24 and 28 weeks and that is screening for gestational diabetes. And gestational diabetes is a specific type of diabetes that can develop late in pregnancy. So we test all pregnant women for it. And even if you had screening in the first trimester, you're going to get screening again in the second trimester. So just because you had it once, you still need it again. So for the test you drink a sweetened liquid, it's called glucola that has exactly 50 grams of glucose, it sounds like, oh, yay. I get to drink some sugar drink. And it's not fun at all. As a matter of fact, it's actually disgusting. To me it was anyway. I think the orange flavor is probably the best. There's also a Cola flavor that's available that some people like. I think all of it is gross, but anyway, you drink this 50 grams of glucose and then we measure your blood sugar 60 minutes after you finish that sweet drink.

Speaker 1: Now you do not need to fast before the test, regardless of what you may hear, you don't need to fast for it. However, if the results are abnormal, then you do need a second test in order to decide with certainty if you have gestational diabetes and for that second followup test, which is a three hour long test, you do need to be fasting for it. So you don't need to be fasting for the initial screening tests and do need to be fasting if you have the followup test. And I've seen some women, this is kind of an aside, sort of think about how to beat or trick this screening test. You know, you don't want to do that if you have gestational diabetes, you want to know if you have gestational diabetes. So don't feel like you have to do anything to try and trick the results of the test.

Speaker 1: If you have it, you have it. And you want to be able to take care of it because there are some consequences to gestational diabetes. And it's on my list of podcast episodes to do actually. So just go ahead and do the test without worrying you know, what or how you can influence the results. The other thing we do at the same time, usually we draw your blood for the blood glucose tests for the glucola screening is that we repeat your blood count, your complete blood count, your CBC, in order to have a bit more of an accurate assessment closer to delivery. Again, it's usually done at the same time as you get your blood drawn to get the results of the glucose screening.

: All right. And then lastly is the third trimester and the third trimester is greater than 28 weeks. And really the only test that is done in the third trimester is GBS. GBS is also known as group B strep or group B streptococcus or group beta streptococcus. It's a common bacteria that about 15 to 40% of pregnant women carry. It's not a cause for concern outside of pregnancy. However, for pregnant women this bacteria could hurt your baby during labor and childbirth. It's not very frequently that it happens. So we test all pregnant women for between 35 and 37 weeks of pregnancy with the vaginal and rectal swab. I actually did a whole podcast episode about this. It is episode number 31 on GBS and I will of course link to that in the show notes.

: Now one thing you will notice that I did not say that you need in the third trimester is another ultrasound. That is not routinely recommended for most people that you need another ultrasound towards the end of pregnancy. There are a lot of doctors who order repeat ultrasounds fairly routinely just to check on the growth of the baby. But those are notoriously inaccurate for estimating weight. So they are not recommended. Now, if you have issues with your pregnancy, if you have hypertension, if you have diabetes, if there has previously been some concern about growth, then yes, an ultrasound is absolutely appropriate. But routinely for a pregnancy that's going along just fine with no issues then an ultrasound in the third trimester is not recommended or needed.

: Okay, so to summarize in the first trimester and that's where you get most of the stuff done, so that initial blood work, typically at that initial visit it's going to be a complete blood count. Your blood type, hepatitis, rubella testing for transmitted infections including syphilis and perhaps gonorrhea or chlamydia. You'll get a urine analysis and a urine culture. Most folks will have an ultrasound in the first trimester as well in order to get the most accurate assessment of how far along you are. An estimate of the due date, noninvasive prenatal testing or nip screening. Genetic testing can be done in the first trimester and then depending on if you have risk factors, you may also get diabetes testing as well. In the second trimester, you will get your anatomy ultrasound or morphology, ultrasound level two ultrasound. But the big ultrasound to look at all the structures of your baby to make sure everything is growing appropriately. And you will also get gestational diabetes screening between 24 and 28 weeks. Oh and I forgot to say that anatomy ultrasound is between 18 and 22 weeks, best done at about 20 weeks. And then in the third trimester you get testing for GBS or group beta strep.

Speaker 1: All right, so that is it for this episode of the podcast. Remember that you can get all of this information for you in a handy guide that you can print out. Go to www.ncrcoaching.com/prenatal to download that guide. Also be sure to subscribe to the podcast in Apple podcasts, Spotify or wherever you listen to podcast. And I would love it if you leave me a review in Apple podcasts. I love reading the reviews. They always warm my heart. It also helps other women find my show and it helps the show to grow. So definitely do that for me. If you have a minute, leave an honest review in Apple podcasts and don't forget about the free Facebook group, All About Pregnancy and Birth. You can search for that on Facebook or the link to join us is in the show notes. Great place to be to connect with other pregnant women. My community manager who's a doula, is in the group as well.

: Also, don't forget to check out my free online class on how to make a birth plan that works to help you have the birth that you want. The class is offered every single day, multiple times a day. So go to www.ncrcoaching.com/register to sign up for the class. It is not too early to start thinking about making your birth wishes. Now, next week is the week of Thanksgiving, so I'm taking some time away to spend time with my family. So I'll be rebroadcasting one of my favorite episodes with a little bit of an update. So come on back next week to see which episode it is. And until then, I wish you a healthy and happy pregnancy and birth.

Speaker 2: Today's episode is brought to you by Women's Wellness Coaching by Dr. Nicole Calloway Rankins. Head to www.ncrcoaching.com to check out my free one hour mini course on how to make your birth plan, as well as my comprehensive online childbirth education class, The Birth Preparation Course, with over eight hours of content and a private course community. The Birth Preparation Course will leave you knowledgeable, prepared, confient, and empowered going into your birth. Head to www.ncrcoaching.com to learn more.