Prenatal testing starts the moment you find out you are pregnant and continues throughout your entire pregnancy. Some tests screen for conditions you may have. Others look at your baby’s development and genetics. These tests are valuable tools, but they can also be a source of real anxiety and confusion. There are a lot of different tests, a lot of different names, and a lot of information to navigate.

As a result, this episode is a comprehensive, evidence-based guide to every test offered in the first half of pregnancy. We walk through every test you may be offered through your anatomy ultrasound, what each one can tell you, how accurate it is, and how to make informed decisions. By the end, you will have a clear understanding of your options. In addition, you will feel confident having these conversations with your doctor or midwife. A companion episode covers prenatal testing in the second half of pregnancy.

Listen Now

This episode is made possible with support from our sponsors. I appreciate your support for the brands that help power this podcast.

Article and Resources

The Anxiety of Waiting for Results

Before we get into the tests themselves, I want to name something many expecting parents feel but rarely talk about. There is a certain low-level anxiety that runs underneath pregnancy. So much of it is tied to testing. You wait for an early ultrasound to confirm a heartbeat. Then you wait for genetic screening results. Next you wait for the anatomy scan. Even after every test comes back normal, there is still a sense that you do not truly know everything is okay until your baby is in your arms. I felt this with both of my pregnancies. If you are feeling it too, you are not alone.

You cannot make the waiting disappear entirely. However, 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 to fill. As a result, the goal of this episode is to give you that foundation. That way, every testing decision you make feels like your own.

What Prenatal Tests Can Tell You

Prenatal tests fall into a few general categories based on what they are looking for. For example, some tests monitor your health during pregnancy. These track things like blood pressure, glucose levels, infections, and anemia. Other tests focus on your baby, looking at their growth, development, and genetics. In addition, a third group checks for conditions that could influence your birth. All of these tests are tools your care provider uses to build a picture of your pregnancy. Some are routine and essentially universal. Others are optional and depend on your personal circumstances, family history, and preferences.

Screening Tests Versus Diagnostic Tests

One of the most important distinctions in prenatal testing is between a screening test and a diagnostic test. A screening test tells you the likelihood that a condition is present. However, it does not give you a definitive yes or no. Instead, it combines information from the test itself with other factors, like your age and medical history, to estimate risk. A positive screening result does not mean your baby has a condition. It means there is a higher chance of a positive result. As a result, further testing is worth considering.

On the other hand, a diagnostic test gives you a definitive answer. It confirms whether a specific condition is actually present. Diagnostic tests for genetic conditions are invasive and carry some risk. For this reason, providers typically only offer them after a positive screening result or when family history suggests the need.

This distinction matters because getting back a positive screening result can feel devastating in the moment. It is easy to jump to conclusions. However, a screen is not a diagnosis. Many people who receive a positive screen go on to have perfectly healthy babies. As a result, the screen is a starting point for further conversation with your care provider, not an answer.

Noninvasive Versus Invasive Tests

The other useful distinction is whether a test is noninvasive or invasive. Noninvasive tests do not pose a risk to you or your baby. For example, these include urine samples, blood draws, ultrasounds, and swabs. If you are anxious about needles, a blood draw may not feel particularly noninvasive, and that is fair. However, if blood draws are hard for you, let your doctor or midwife know. You can ask for someone experienced. That way, you are not sitting with a first-day intern while they try to find a vein.

Invasive tests carry some risk because they involve accessing fluid, tissue, or cells from inside the uterus. The main invasive tests in pregnancy are chorionic villus sampling, amniocentesis, and cordocentesis. However, most prenatal testing is noninvasive. Providers typically only offer invasive tests after a positive screening result or when there is a known genetic risk in your family.

Understanding Test Accuracy

No test is 100% accurate. As a result, a few key terms will help you make sense of every test in this episode. First, sensitivity is how often a test correctly identifies a condition when it is actually present. For example, a test with 99% sensitivity correctly flags 99 out of every 100 affected babies. The remaining 1 baby would receive a false negative, meaning the test missed the condition.

Specificity is the flip side. It is how often a test correctly rules out a condition when it is not present. For example, a test with 99% specificity correctly clears 99 out of every 100 babies who do not have the condition. The remaining 1 person would get a false positive. In other words, the test flagged a condition that is not actually there.

Positive predictive value, often shortened to PPV, is the term that matters most. It is the probability that a positive result is actually a true positive. PPV depends heavily on how common the condition is in the group being tested. For rare conditions, even a highly accurate test can have a surprisingly low PPV. This means a positive result is more likely to be a false alarm than people often realize. We will come back to this when we talk about genetic screening, because it is essential for understanding what a positive result actually means.

Urine Testing

Urine analysis is a quick, noninvasive test that gives your care provider a lot of information. Your doctor or midwife dips a test strip into your sample of urine or sends it to a lab. This checks levels of glucose, protein, ketones, and bacteria. These markers can flag risk for 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. Whether you have additional urine tests depends on your care provider. In addition, it depends on whether anything in your initial results warrants tracking.

Routine Blood Work

A standard first-appointment blood draw checks a lot at once. For example, this single sample can tell your care provider about your blood type, your immunity to certain infections, and your risk for several conditions. In addition, you may need additional blood tests later in pregnancy. These can monitor for anemia or screen for infections if a concern arises. Let’s walk through what is in a typical prenatal blood panel.

Blood Type and Rh Factor

Your blood type (A, B, AB, or O) does not affect your pregnancy. However, it is important to know if you ever need a blood transfusion. More relevant to pregnancy is your Rh factor, which is a protein on your red blood cells. You are either Rh-positive, which is the most common, or Rh-negative.

Rh-negative status varies significantly by ethnicity. According to a large American Red Cross study of over 3 million donors, around 17% of white Americans are Rh negative. By comparison, about 7% of Black and Hispanic Americans are Rh negative, and rates are even lower in people of East Asian descent.

In a first pregnancy, an Rh incompatibility usually does not cause problems. The first time your blood encounters your baby’s Rh-positive blood, your immune system produces antibodies. We call this first exposure sensitization. Sensitization can also happen through other events that expose your blood to Rh-positive blood, such as a miscarriage, an ectopic pregnancy, an amniocentesis or CVS, or abdominal trauma during pregnancy. Once your immune system has been sensitized, it stays primed to produce antibodies the next time it encounters Rh-positive blood. As a result, in subsequent pregnancies, those antibodies can cross the placenta, attack a baby’s red blood cells, and cause serious complications.

The standard treatment for Rh incompatibility is Rho(D) immune globulin, most commonly known by the brand name RhoGAM. RhoGAM blocks this initial immune response, so your body never builds up antibodies in the first place. Your provider typically gives RhoGAM around 28 weeks of pregnancy. Then you receive another dose after birth if your baby is Rh positive. In addition, your provider may give additional doses after events that could expose your blood to fetal blood, such as bleeding, trauma, miscarriage, or an invasive test like amniocentesis.

If the baby’s father is also Rh negative, your baby will be Rh negative, which means Rh incompatibility does not apply. However, paternal status is not always known with certainty. As a result, ACOG now recommends fetal RhD genotyping via cfDNA as the most reliable way to determine your baby’s actual Rh status. Fetal RhD genotyping using cell-free DNA can analyze fragments of your baby’s DNA in your bloodstream. This determines your baby’s Rh status as early as 10 weeks. If the test confirms your baby is Rh negative, RhoGAM is not needed. About 40% of Rh-negative mothers carry an Rh-negative baby. As a result, a meaningful number of women could potentially avoid unnecessary RhoGAM doses.

In an August 2024 Clinical Practice Update, ACOG formally supported the use of cfDNA for fetal RhD genotyping. The update cited a recent meta-analysis showing a pooled sensitivity of 99.3% and a specificity of 98.4%. In other words, this is a very accurate test.

In 2023, there was a RhoGAM shortage in the United States. As a result, ACOG issued a Practice Advisory supporting cfDNA-based fetal RhD genotyping as a way to conserve supply. The advisory stated that if cfDNA confirms an Rh-negative fetus, RhoGAM is not needed antepartum.

Fetal RhD genotyping via cfDNA is not yet the standard approach everywhere in the United States. Availability varies by practice and insurance coverage. However, it has been routine in parts of Europe for years. If you are Rh negative, it is worth asking your doctor or midwife whether this testing is available to you.

Infectious Disease Screening

Your first-appointment blood panel also screens for a handful of infectious diseases. These tests matter because some infections can cross the placenta or be transmitted during birth. In addition, many of these are treatable with early detection. Most are universal and run as a standard panel rather than as optional.

The typical panel includes HIV, syphilis, hepatitis B, and often chlamydia and gonorrhea. In addition, your provider checks your immunity to rubella (also known as German measles) and varicella (chickenpox). These viruses can cause serious fetal complications if you contract them during pregnancy. If you are not immune, your care provider will likely recommend vaccination after birth.

Blood Counts, Iron, and Hemoglobin

A complete blood count, often shortened to CBC, is part of standard prenatal blood work. Your iron levels and hemoglobin tell your provider how well your blood carries oxygen. In addition, they show whether you are at risk for anemia. Anemia is a condition where you do not have enough healthy red blood cells to carry adequate oxygen throughout your body. The most common cause of anemia in pregnancy is iron deficiency. This happens because your blood volume expands significantly, and your iron needs increase. Other less common causes 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. In addition, your provider typically repeats a CBC later in pregnancy. This usually happens around the time of gestational diabetes screening.

Glucose levels in this initial blood draw also give your provider a baseline. Elevated levels may warrant gestational diabetes screening earlier than it is routinely offered.

Carrier Screening

Carrier screening is a genetic test that checks whether you carry genes for specific inherited conditions. Most of these conditions are recessive. This means a child would need to inherit the gene from both parents to have the condition. If only one parent is a carrier, a child is not at risk, though the child may also be a carrier.

Carrier screening tests for conditions like cystic fibrosis (a lung and digestive disease), spinal muscular atrophy (a motor neuron condition), sickle cell disease, Tay-Sachs disease, and various forms of thalassemia (blood disorders). Most of these conditions are individually rare. However, being a carrier is much more common than having the condition. For example, cystic fibrosis affects approximately 1 in 2,500 to 3,500 white newborns in the United States, with much lower rates in other ethnic groups. About 1 in 25 people of European descent carry a cystic fibrosis gene variant. SMA carrier frequency is around 1 in 50 across the general population.

Carrier screening is most often done during pregnancy, especially at the first prenatal appointment. It is a simple blood or saliva test from you. If you carry a specific condition, your partner is typically tested next to determine the actual risk to your baby. You can also do carrier screening before conception, which gives you the most flexibility. However, this is not the timing most parents come into it. There is nothing wrong with starting this conversation during pregnancy.

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. ACOG also recommends a complete blood count and screening for hemoglobinopathies like sickle cell disease and thalassemia. Beyond these core recommendations, your provider may offer an expanded carrier screening panel. These panels test for dozens to hundreds of conditions.

The landscape of carrier screening has shifted significantly in recent years. Historically, providers used an ethnicity-based approach, offering certain tests based on ancestry. For example, Tay-Sachs disease was routinely offered to people of Ashkenazi Jewish descent. However, that approach has limitations in an increasingly multi-ethnic population, where people often do not fit neatly into one ethnic category. As a result, the American College of Medical Genetics and Genomics has moved toward what it calls a tiered approach. Specifically, ACMG recommends that all patients, regardless of ethnicity, be offered Tier 3 screening. This panel includes 113 conditions chosen for their severity and carrier frequency.

ACOG considers ethnicity-based, panethnic (offered to all patients regardless of ethnicity), and expanded carrier screening all acceptable approaches. The key is that each practice establishes a consistent standard. In addition, a recent commercial laboratory study of over 20,000 patients tested with the ACMG 113-gene panel found something striking. Specifically, 57.5% of patients were carriers for at least one of the conditions on the panel. This high positivity rate underscores the importance of partner testing when you do carrier screening.

The practical takeaway is that expanded carrier screening is increasingly available and increasingly covered by insurance. If you are interested, ask your provider what panel they offer and whether a broader panel is available. A positive result does not mean your baby will have the condition. It means further testing for your partner is a reasonable next step. If both of you test positive for the same condition, a meeting with a genetic counselor can help you understand what the results mean for you.

Screening for Chromosomal Abnormalities

Beyond carrier screening, there is a separate category of prenatal genetic screening focused on chromosomal abnormalities in your baby. These conditions happen when a baby has an extra or missing chromosome, which is known as aneuploidy. The most well-known is trisomy 21, or Down syndrome. This occurs when a baby has an extra copy of chromosome 21. Other examples include trisomy 18 (Edwards syndrome) and trisomy 13 (Patau syndrome). In addition, chromosomal abnormalities also include conditions involving the sex chromosomes, like Turner syndrome and Klinefelter 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 age or baseline risk. This is a big shift from older guidelines. Specifically, older guidelines limited routine screening to patients over 35 or with other risk factors. As a result, the decision of whether to pursue testing, and which approach to take, is now squarely a patient-centered choice after counseling.

Cell-Free DNA Screening

Cell-free DNA screening, often called cfDNA screening, is the most accurate screening test for the common chromosomal abnormalities. You may have heard it referred to as NIPT, which stands for noninvasive prenatal testing. However, that term is being phased out. The reason is that NIPT can falsely imply the test is diagnostic. It is not. cfDNA is a highly accurate screening test, but a positive result still requires confirmation through diagnostic testing. As a result, the more current term is simply cfDNA screening, or prenatal screening with cfDNA.

Here is how it works. During pregnancy, small fragments of your baby’s DNA circulate in your bloodstream. These fragments come primarily from the placenta. As a result, a simple blood draw from you is enough to isolate and analyze them. There is no risk to your baby from the test itself. cfDNA screening can be done as early as 10 weeks of pregnancy. In addition, results are typically available within one to two weeks.

The core purpose of cfDNA is to assess risk for trisomy 21, trisomy 18, and trisomy 13. In addition, most labs offer screening for sex chromosome aneuploidies, like Turner syndrome or Klinefelter syndrome. Almost all labs will determine the biological sex of your baby as part of the result. Some labs also offer screening for microdeletions. These are very small missing pieces of chromosomes that can cause specific syndromes.

The Society for Maternal-Fetal Medicine made a strong recommendation in 2025 that has also been endorsed by ACOG. Specifically, SMFM recommended that cfDNA screening for the common trisomies be made routinely available to all obstetrical patients. In addition, SMFM recommended that sex chromosome aneuploidy screening be opt-in. The reason is that false-positive rates are higher under these conditions. For microdeletions, SMFM recommended against routine cfDNA screening. Instead, patients interested in this information should be offered diagnostic testing.

Accuracy on the common trisomies is very high. A systematic review and meta-analysis of over 100 studies found a sensitivity of 99.3% for trisomy 21. In addition, it found 97.4% for trisomy 18 and 97.4% for trisomy 13. Specificity was very high across all three. These figures came from research that built on the landmark NEXT trial published in the New England Journal of Medicine. The NEXT trial compared cfDNA to standard first-trimester screening in nearly 16,000 women across an average-risk population. As a result, the trial demonstrated that cfDNA outperformed standard screening even in the average-risk group. That finding is the foundation behind the 2020 ACOG shift to recommending cfDNA for all patients.

Translating accuracy into practical numbers helps make sense of it. cfDNA behaves differently across populations. For example, in a hypothetical high-risk population of 10,000 pregnancies, researchers estimated cfDNA would correctly identify 324 cases of Down syndrome. It would miss 9 and produce 31 false positives. By contrast, in a hypothetical lower-risk population of 100,000 pregnancies, it would identify 417 cases with 94 false positives. In other words, the test is more accurate in higher-risk populations. This is because positive predictive value depends on how common a condition is in the group.

That brings us back to PPV. Because the common trisomies are relatively rare, even a highly accurate screening test can produce false positives. For example, a positive cfDNA result for trisomy 21 in a younger, lower-risk patient has a PPV around 80 to 90%. This means 10-20% of positives are false alarms. For rarer conditions and microdeletions, PPVs are much lower. A New York Times analysis examined the most commonly offered microdeletion tests. The analysis estimated that positive results were incorrect about 85% of the time. As a result, current guidance does not recommend routine microdeletion screening. In addition, any positive screening result deserves a careful conversation with your doctor, midwife, or a genetic counselor before making further decisions.

A few other important notes on cfDNA. In twin pregnancies, cfDNA is now a first-line option for screening for trisomy 21. In addition, detection rates for trisomies 18 and 13 are also high. However, in triplet or higher-order pregnancies, cfDNA is not recommended.

Some cfDNA tests return as non-reportable, which means the lab could not produce a clear result. This can happen for a few reasons. For example, low fetal fraction (not enough of your baby’s DNA in the sample) is one cause. In addition, high maternal body weight or other factors can affect the result. Some studies have associated non-reportable results with a slightly higher risk for aneuploidy, though research on this is mixed. As a result, current guidance recommends following up with genetic counseling. In addition, considering further evaluation is a reasonable next step if the result is non-reportable.

Finally, cfDNA can detect your baby’s Rh status, which ties back to the fetal RhD genotyping discussed earlier. In addition, cfDNA will determine your baby’s biological sex. If you want the sex of your baby to be a surprise, be sure to let your provider know before the results come back.

One thing worth being aware of: the labs that perform cfDNA screening have a financial interest in expanded use of these tests. As a result, some of the broader messaging around prenatal screening reflects that. cfDNA is a useful tool, and current guidelines recommend offering it to all patients for sound clinical reasons. However, knowing that there are commercial incentives in the system can help you approach decisions with a more balanced viewpoint.

Serum Screening Options

Before cfDNA became widely available, serum-based screening tests were the standard approach to genetic screening. They are still used in specific situations. For example, providers may use them when cfDNA is not available, not covered by insurance, or cannot be performed reliably. In addition, some patients prefer them after counseling.

The first-trimester screen combines a blood test of two markers from you with an ultrasound measurement of your baby’s nuchal translucency. Specifically, this is the fluid collection at the back of your baby’s neck. Babies with Down syndrome often have an increased amount. This test is done between 11 weeks and 13 weeks 6 days. The combined detection rate for the common trisomies is roughly 85%, with a false positive rate of about 5%.

The quad screen is a maternal blood test that measures four substances: alpha-fetoprotein, hCG, estriol, and inhibin A. It is done between 15 and 22 weeks. In addition to screening for trisomies 21 and 18, the quad screen can flag risk for neural tube defects like spina bifida. It is somewhat less accurate than the first-trimester screen. An integrated screen combines results from both the first and second trimester tests. As a result, it has a higher detection rate than either test alone. However, results are not available until after the second-trimester component is complete.

If you are choosing between cfDNA and serum screening, cfDNA is more accurate for the common trisomies. However, serum screening can offer information cfDNA does not, like risk for neural tube defects. Current guidance is that you should have one screening approach, not multiple simultaneously. The reason is that multiple screens can produce contradictory risk estimates.

The Anatomy Ultrasound and Soft Markers

The anatomy scan is a detailed ultrasound typically performed between 18 and 22 weeks. The technician takes a detailed look at your baby’s organs, measurements, and structural development. This is one of the most significant tests during pregnancy. It checks for a wide range of structural abnormalities. In addition, this is often the point where parents find out the biological sex of their baby. Many parents have already learned this from cfDNA. The anatomy scan also helps identify neural tube defects, heart defects, and other structural differences.

Sometimes the anatomy scan picks up what we call soft markers. These are small findings that can occur in some chromosomal conditions. However, they also occur frequently in healthy babies. In the cfDNA era, an isolated soft marker in someone with a normal cfDNA result is now typically considered a normal variant. Most babies with these findings are completely healthy. In addition, their development is not affected.

A few common soft markers come up often enough that it helps to know what they are. For example, an echogenic intracardiac focus is a small bright spot in the heart. It almost always disappears on its own and has no impact on heart function. A choroid plexus cyst is a small fluid-filled space in the part of the brain that produces spinal fluid. These typically resolve before birth. Shortened long bones refers to a single ultrasound measurement of arm or leg bones being on the smaller side for gestational age. However, most babies with this finding go on to grow and develop completely normally. Research supports the current guidance that isolated soft markers do not predict abnormality at birth or beyond, in the setting of normal genetic screening.

If a soft marker comes up and you have not had cfDNA, a conversation with your provider about next steps makes sense. In addition, if a marker is paired with another finding, your provider may recommend a more detailed evaluation.

Diagnostic Testing for Genetic Conditions

Up until now, we have been discussing screening tests, including the anatomy ultrasound. However, if a screening test comes back positive, your care provider may offer diagnostic testing. Family history or another factor can also lead to this conversation. Diagnostic tests can confirm with near certainty whether a specific genetic condition is present. The two primary diagnostic tests in pregnancy are chorionic villus sampling and amniocentesis. Both involve collecting a sample for analysis. In addition, both carry a small risk of miscarriage. A third, less common diagnostic test is cordocentesis, which collects a small sample of fetal blood from the umbilical cord.

Like screening tests, diagnostic testing is optional. In fact, every prenatal test is optional, and you can decline any of them at any point. However, diagnostic testing in particular is something many parents weigh carefully because of the small associated risks. Some parents are comfortable with the uncertainty. Others choose not to pursue a diagnostic test because the information would not change how they want to proceed. On the other hand, other parents want a definitive answer so they can plan. This is a personal decision, and there is no wrong choice.

Chorionic Villus Sampling

One diagnostic test is chorionic villus sampling, usually abbreviated as CVS. This test can detect chromosomal abnormalities and genetic disorders. The window for CVS is relatively short. Specifically, providers typically perform it between 10 and 13 weeks of pregnancy. CVS involves collecting a small sample of placental tissue from where the placenta attaches to the uterine wall.

There are two approaches to this procedure. First, in the transcervical method, ultrasound guides a thin catheter through the cervix to the placenta, and cells are gently suctioned. This approach may not be suitable for some women. For example, women with uterine fibroids or a significantly tilted uterus may not be candidates. In those cases, providers use the transabdominal approach instead. Specifically, ultrasound guides a long, thin needle through the abdomen. The actual sample collection takes only a few minutes. The whole procedure takes about 30 minutes. In addition, results are typically available within five to seven days.

Accuracy for detecting chromosomal abnormalities is very high, around 98 to 99%. Like all diagnostic tests, CVS does not predict the severity of a condition, only whether it is present. The primary risk is miscarriage. An older 2015 systematic review and meta-analysis estimated the procedure-related risk at about 0.22%. A more recent 2019 meta-analysis of large controlled studies found procedure-related miscarriage rates of 0.20% for CVS and 0.30% for amniocentesis.

The experience of the provider performing the test and how frequently this test is performed at a facility both meaningfully affect risk. For example, a large national registry study from Denmark analyzed over 64,000 procedures. The study found that departments performing fewer than 1,500 procedures over 11 years had higher miscarriage rates. Higher-volume centers tend to have lower complication rates. As a result, if you are considering CVS or amniocentesis, it is reasonable to ask about your provider’s experience and the volume of procedures performed at the facility.

Other possible side effects include spotting, cramping, and pain at the puncture site. However, if you have a CVS and develop a fever, chills, or leaking amniotic fluid, contact your care provider right away. You should know that these complications are rare.

Amniocentesis

Amniocentesis, often shortened to amnio, happens later in pregnancy than CVS. Specifically, providers typically perform it between 15 and 20 weeks. Your provider uses ultrasound guidance to insert a thin needle through your abdomen into the amniotic sac. This collects a small sample of amniotic fluid. The fluid contains cells shed by your baby. As a result, the sample can reveal chromosomal abnormalities, genetic disorders, and neural tube defects. The actual fluid collection takes less than five minutes. The full procedure takes about 45 minutes. In addition, 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 amniocentesis over CVS is that it can also screen for neural tube defects. Specifically, amniocentesis measures alpha-fetoprotein levels in the amniotic fluid. As with CVS, the primary risk of an amniocentesis is miscarriage. The 2015 meta-analysis placed the procedure-related risk at about 0.11%. The 2019 meta-analysis estimated it closer to 0.30%. Both figures are low. In addition, the risk is lower at experienced centers that perform many procedures each year.

Other potential side effects include some cramping or minor irritation around the puncture site. In addition, you may feel a sharp pain when the needle enters your skin and again when it enters the uterus. Rarely, women experience fever, chills, heavy cramping, or leaking fluid. These last symptoms can be signs of infection or other complications. As a result, they warrant a call to your provider.

Cordocentesis

Cordocentesis, also known as percutaneous umbilical cord blood sampling, is a much less common diagnostic test. It uses ultrasound to guide a thin needle into the umbilical cord. This collects a small sample of fetal blood. Because the sample is blood rather than fluid or cells, results are generally available quickly, often within 72 hours.

Cordocentesis is usually reserved for specific situations. For example, providers use it when amniocentesis, CVS, or ultrasound have not produced a clear answer. In addition, cordocentesis is appropriate when fetal blood is specifically what is needed for diagnosis. The most common current indication is suspected fetal anemia. Cordocentesis can also detect chromosomal abnormalities and blood disorders. In addition, it can help diagnose certain fetal infections and evaluate fetal wellbeing in specific high-risk situations. Providers perform cordocentesis after 17 weeks of pregnancy. The primary risk is miscarriage, with rates reported around 1.3%. This is higher than CVS or amniocentesis. Other possible complications include blood loss from the puncture site, infection, fetal heart rate changes, and premature rupture of membranes. As a result, cordocentesis use has become uncommon as other testing options have improved.

Paternity Testing During Pregnancy

Paternity testing during pregnancy is something some parents need or want, and there are options. For example, cell-free DNA can confirm paternity. The noninvasive prenatal paternity test (NIPPT) uses the same technology as cfDNA aneuploidy screening. The test requires a blood draw from you and a sample from the potential father. In addition, providers can perform it from about 8 weeks of pregnancy. NIPPT is highly accurate, with reliability above 99% in clinical studies.

Genetic Counseling

As you can see, there are a lot of tests available, and this can all feel confusing and overwhelming. In some cases, you may consider meeting with a genetic counselor. A genetic counselor is a trained healthcare professional. They specialize in translating genetic information into practical understanding. Meeting with a genetic counselor can be especially valuable in a few situations. For example, you may benefit if you have a family history of a genetic condition. In addition, a genetic counselor can help if you have received a positive screening result. Other situations include considering expanded carrier screening or navigating preimplantation genetic testing as part of IVF.

If you are pregnant at 35 or older, your provider may bring up genetic counseling as an option. There is a full episode that offers a deep dive into how age affects pregnancy. So before you panic, listen to that episode. Pregnancy at 35 and beyond is increasingly common. In addition, most pregnancies in this age range proceed completely normally.

A genetic counselor can help you understand what a test actually tells you and does not tell you. In addition, they can walk you through probabilities and implications in plain language. If your provider has not specifically offered a referral to a genetic counselor and this is something you would like, please ask for one. Your provider should be able to refer you to a genetic counselor who can help you navigate this in more detail.

Navigating Your Testing Options

Most of this episode has focused on what the tests are. The rest is about how to approach them as a patient. This involves knowing your options, costs, planning ahead, and everything else that goes into making testing decisions. In addition, your testing options are often broader than what is first presented to you.

Informed Consent

One of the most important things to understand about any prenatal test is that every single test should come with informed consent. This means your provider explains what the test is, why they are offering it, what the results can and cannot tell you, any risks, and any alternatives. In addition, you always have the right to decline any test.

Providers, doctors, midwives, hospitals, and practices all have their own policies, procedures, and routine protocols. Testing is often wrapped up in those routines, and you can find yourself put on a track. They will tell you what they want to do, and a lot of times parents go along with that. If that is the case for you, that is great. However, just because something is routine does not mean you do not have a choice in it. You always do.

Plan Ahead So You Can Get Informed

If you show up to an appointment and a test is being run that day, it can feel like you do not have a lot of choices. However, if you know that a test is coming up, you have time to educate yourself. In addition, you can talk it through with your partner. You can decide whether you want to opt in, opt out, or have more discussion with your care provider. As a result, this makes you a much more active participant in your prenatal care. Asking ahead of time what tests are coming at your next visit is a simple way to make sure nothing catches you off guard.

Following your pregnancy week-by-week is one of the best ways to stay ahead of what is coming. The 40 Weeks podcast has a short episode for each week of pregnancy. It covers what to expect at upcoming appointments, what is happening with your baby, and what decisions are ahead. In addition, if a test is coming up at your next visit, the 40 Weeks episode for that week will let you know.

Including Your Partner

Prenatal testing decisions are ultimately yours. However, these decisions, testing results, and all of it are easier to navigate when you are not doing it alone. I highly recommend your partner join you for appointments. They can help you think through options and ask questions you may not think of in the moment. Your partner can also advocate for you if you have questions or concerns about any particular test. If your partner cannot be there in person, even a phone or video call during appointments can help.

Carrier screening is one place where partners are often directly involved. The reason is that a positive result in you typically leads to testing for your partner. The anatomy scan is another appointment where having your partner there can make a big difference. The reason is that findings often come up in real time during the ultrasound itself. Beyond that, if you ever get back unfavorable or unexpected results during an appointment, that can be a really stressful moment. As a result, having your partner with you means you have someone there to support you in real time. That way, you are not getting hard news alone.

Interpreting Results

Before any test, ask your provider when you can expect results and how you will receive them. Many providers only contact patients for abnormal results. As a result, if you hear nothing, it often means everything is normal. However, it can be really difficult to wait for a test result when you are anxious about it. If you are not hearing back from your care provider, you can always follow up with them.

If a result is confusing, ask for an explanation. For example, some tests return as positive or negative. Others give a probability or risk score. In addition, a few (like cfDNA for microdeletions) require careful interpretation. If you receive a positive screening result, the next step is usually a conversation about diagnostic testing or genetic counseling. Remember that a positive screening test only indicates that you may want to consider further testing. It does not diagnose anything.

Talking With Your Doctor or Midwife

The single most important thing you can do with everything in this episode is talk to your doctor or midwife. They know your history and can interpret results in your context. Do not be intimidated to speak up and ensure all of your questions and topics get addressed. Your doctor or midwife is your trusted partner in navigating your prenatal care. As a result, the more clear and open conversations you have with them, the more confident you will feel in your decisions.

A Final Note

Prenatal testing is a powerful set of tools, and it also carries real emotional weight. If you felt a little anxious going through all of these tests, that is completely normal. However, you do not need to understand every specific detail about all of these tests ahead of time. This episode should give you a great baseline of information. As a result, you can have a productive conversation with your provider and land on the choices that feel right for your family.

This episode covered prenatal testing in the first half of pregnancy, through the anatomy ultrasound. Testing in the second half of pregnancy is its own conversation. The reason is that it has a different character and different decisions involved. For example, many of those tests produce results in real time and can directly affect your birth plan. Stay tuned for the next episode on prenatal tests in the second-half of your pregnancy.

Thank you to the brands that help power this podcast.