Testing 1, 2, 3: Which of the Prenatal Tests Are Necessary?

Not every prenatal test that your health-care provider suggests is necessary. We review the five you definitely need and give you the real deal on those you don’t.

By Judith A. Lothian, RN, PhD, LCCE, FACCE, and Charlotte DeVries

Adapted from The Offical Lamaze Guide: Giving Birth with Confidence

These days, it can seem like your doctor has another round of prenatal testing every time you go in for an exam. OB/GYNs and midwives used to check only a few vital statistics throughout a woman’s pregnancy, but during the past 20 years, the extent of prenatal testing has increased dramatically. Yet not everyone in the medical community agrees that all of these extra tests are of
value. Instead of being vigilant about picking up on problems, many health-care providers (doctors far more than midwives) over-test because they fear liability and simply expect trouble.

Many of these newer tests were created to diagnose problems in high-risk pregnancies. But with the increased medicalization of pregnancy, they have become routine for healthy women with no known risks. This does not mean that every test is right for everyone, however, or that they are risk-free themselves. There may be a problem that prenatal testing doesn’t show, or a
problem may not exist even if the test suggests it does. Results that are unclear or even misleading can plague your peace of mind and decrease your confidence. The barrage of tests can also make you feel like your health-care provider knows everything there is to know about your pregnancy, which is not the case.

This list details the prenatal testing that is considered essential by everyone, as well as other tests that you’re likely to encounter during the next few months. You have the right to ask about and understand why each test is being recommended, the particulars of how a test will be done, all the risks associated with a test and if there are less risky approaches to diagnosing a problem or concern. Your health-care provider should let you know that you have a right to refuse a test, and he should welcome your questions and respect your decisions.

The Essentials

BLOOD PRESSURE CHECKS are necessary because rising blood pressure, especially in the last trimester, can indicate pregnancy-induced hypertension (also called preeclampsia or pretoxemia), which, if not treated, can be dangerous for you and your baby.

WEIGHT CHECKS make sure that you’re gaining enough weight for your baby’s health; they are not to keep you from gaining too much. And by tracking the growth of the uterus, your health-care provider can make sure that your baby is growing well. If your uterus gets larger more quickly than expected, it may indicate something quite different: multiples.

BLOOD TESTS identify a number of factors, including your blood type and cell count, iron level, immunity to chicken pox and other diseases, and Rh factor, as well as certain sexually transmitted diseases or infections. They are considered standard and acknowledged as important by all because they help established your overall wellness.

URINE TESTS monitor the status of sugars and proteins in your body. High sugar levels may suggest diabetes, and high proteins in your body can indicate a treatable bladder infection. Protein in the urine, especially in the last trimester, can indicate pregnancy-induced hypertension (see above).

Although simple urine tests have been done routinely for years, there is little data to show that they are important for healthy women, especially if they don’t have high blood pressure.

FETAL HEART TONES can be monitored by your health-care provider with a fetoscope (a type of stethoscope) or handheld Doppler device. This test may reassure you that all is well, but your own knowledge of your baby’s movements throughout the day and night is equally important. There is no need for sonograms or electronic fetal monitoring to test these indicators.

The Others

CERVICAL CHECKS are invasive and provide little useful information on their own early in pregnancy, and there is no evidence that they should be a routine part of prenatal care. A pap smear can diagnose sexually transmitted diseases and other infections, but so can a blood test. The only time a cervical check may really help is if you are two weeks past your due date and your health-care provider is trying to determine if induction is appropriate.

ULTRASOUND EXAMINATIONS (sonograms) create a picture of a baby inside the womb using the sound waves that are produced by moving a transducer (like a computer mouse) across the mother’s abdomen. They are often used to determine a due date or to attempt to diagnose problems, but they are not always reliable. Misread sonogram results may lead to unnecessary or incorrect interventions.

For example, the nuchal translucency test uses ultrasound to measure the clear (hence, translucent) space in the tissue at the back of the baby’s neck. Doctors use this measurement to assess the baby’s risk for Down’s syndrome and other chromosomal abnormalities. But the diagnosis isn’t definite: The ultrasound isn’t directly testing for chromosomal problems or telling you for sure if your baby has normal chromosomes. Instead, it just gives you a better idea of the statistical likelihood that your baby will have a problem. Plus, a normal result isn’t a guarantee that everything is okay (just that a problem is unlikely), and an abnormal result doesn’t mean that your baby has a problem (just that he has an increased risk of one). It may only cause you unnecessary worry or, unfortunately, false joy.

Both the World Health Organization and the National Institutes of Health agree that routine ultrasound testing during pregnancy has not been sufficiently evaluated to go unquestioned. There is strong disagreement on the effect of ultrasound waves on a fetus. In fact, the Food and Drug Administration has declared that “prenatal ultrasounds can’t be considered completely innocuous,” and the American College of Obstetricians and Gynecologists says that casual use of ultrasound during pregnancy should be avoided.

CHRONIC VILLUS SAMPLING (CVS) attempts to detect some birth defects by looking for chromosomal abnormalities. It is not routinely offered, but can be done at around 10 to 12 weeks to check for certain disorders, such as Down’s syndrome, in everyone who is tested. CVS also includes assessment for such conditions as cystic fibrosis or sickle cell anemia if your baby is thought to be at risk, but it can’t detect neural tube defects, such as spina bifida. There is a small chance of getting a false-positive (a result that incorrectly indicates that there might be something wrong), so CVS often leads to amniocentesis (see below) for confirmation. When the test is done too early in pregnancy, it has been associated with limb defects, such as missing fingers or toes, and miscarriage.

MATERNAL SERUM SCREENING TESTS, including the Alpha-fetoprotein and multiple marker tests such as triple screen, are done at 15 to 20 weeks to look for the presence of proteins or hormones in your blood that may signal a genetic or developmental problem in the baby. These screens have a high rate of false positives that are often discovered when further testing yields different results or when babies are born without problems. The results can cause unnecessary anxiety as well as more tests than needed.

You have a right to refuse these screens. Before you decide, think about what you would do with the results. If you don’t want to take the next step, amniocentesis (see below), it makes sense to consider not having these screens at all. If you have a family history of genetic diseases, including neural tube defects, you might consider them, but you can decline.

AMNIOCENTESIS is a procedure in which a small amount of fluid and cells is taken from the amniotic sac surrounding the fetus and tested to discover if the baby has Down’s syndrome or other birth defects. Many women, especially those over 35, are pressured to have this test. What may not be emphasized is that it is invasive and puts a woman’s body and baby at risk for infection, possibly causing bleeding, the leaking of more amniotic fluid, premature labor, fetal distress and even miscarriage.

Again, it is crucial to think about what you will do with the results before you agree to an amniocentesis. If the information will not change the course of your pregnancy in any way, then the test may not be worth having. However, you may find it helpful to know in advance that your baby might have a problem. Decide what’s best for you.

GLUCOSE SCREENING is a test for gestational diabetes, which is diagnosed in about 5 percent to 7 percent of women. Taken at 24 to 28 weeks, you drink a special sugar mixture, and an hour later, a blood sample is drawn and measured for its glucose level. If it’s too high, you may have gestational diabetes. It’s important to know, however, that your baby needs plenty of glucose, which helps him grow and develop. The only possible downside to this condition is that the baby may get large amounts of it and be big at the time of birth.

You Decide

Midwives in the Netherlands use the term “spoiling the pregnancy” for the unnecessary worry that the false-positive results of prenatal testing can have on a mother-to-be, says Barbara Katz Rothman, author of Recreating Motherhood (Rutgers University Press). They understand that this misinformation may rob you of joy, peace and a relaxed relationship with the baby you’re carrying inside of you.

So keep that in mind as you’re choosing from the menu of tests presented to you. Routine prenatal testing can medicalize your pregnancy and rob you of your confidence. It may make you feel that your health, happiness and baby’s perfection is ensured, or it may scare you into believing that your baby won’t be born healthy. Either way, prenatal testing cannot guarantee any specific outcome, so it may not be worth the extra emotions it brings.

If you refuse to have some prenatal testing done, remember that you are not the first or the last woman to make this choice. Not everyone needs or wants to know that there may be problems with their baby, and many women don’t want the false alarms and worry. What your doctor sees as an absolutely necessary test may not be what a midwife sees. And it may not be what you see either.

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  1. Kathryn Packard says:

    I planned an unassisted homebirth with my second daughter, but still wanted to have a hospital midwife as a backup plan. I couldn’t tell them I was planning a homebirth at all, let alone unassisted, or they wouldn’t have seen me at all. They tried to tell me that glucose screening, GBS testing, and prenatal Rhogam was mandatory. I told them my first daughter was Rh negative as well and if my second turned out to be positive, I would get the Rhogam shot as soon as she was born. I also told then I thought glucose screening was inappropriate fro someone of my age and health. Their exact words were, “You HAVE to do these tests.” I told them I don’t HAVE to do anything. They said if I didn’t, they wouldn’t keep me on as a “patient” (I wasn’t sick, I was pregnant!). I told them to have a nice day and that they wouldn’t be seeing me again.

    I think it’s ridiculous that healthy women are pressured into all of these unnecessary tests, screenings, and procedures. My daughter was born into my and my fiance’s hands, in our living room, with no one there but us. She has never been vaccinated and has never been to a pediatrician (because there has been no need; she’s 100% healthy). Our bodies work the way they’re supposed to work. OBs need to get over their need to intervene. ACOG should adopt the motto, “Don’t just do something, stand there!”

  2. Alisa says:

    I disagree with listing weight checks as necessary. In consultation with my midwives, I did not have weight checks in my second pregnancy. I have a history of an eating disorder, and weight checks put me at risk of relapse. My midwives agreed that there were plenty of other ways of monitoring my health status and my baby’s growth during pregnancy; although weigh-ins can provide useful information, they were not *necessary*. Also, many providers *do* use weigh-ins as an opportunity to police women’s weight gain (I say this based only on anecdotal evidence, but the anecdotes I’ve heard are pretty frequent and alarming), so women would do well to assess their provider’s attitude and approach before getting on the scale.

  3. Charlotte says:

    I thoroughly enjoy reading your blog, but today’s post left me with a few questions. You mention that several tests are associated with negative side effects, e.g., fetal distress or limb defects, but you haven’t provided us with any numbers to illustrate these possible effects. Perhaps this data does not exist? I also wonder if there is information on the estimated rate of false positives.

    I agree with the thrust of your post; birth is much too medical-ized and I’m sure unnecessary testing occurs. However, I’d really like to weigh the risks of additional testing with the possible benefits and to do that, I need more data.

  4. Jennifer says:

    Weight checks can also point to increased risk of preeclampsia, PIH, and/or HELLP Syndrome. If you experience a rapid weight gain over a short period of time it can point to swelling (edema) associated with this condition. It was really the only symptom that I had before I went into full-blown seizure-inducing eclampsia and HELLP syndrome. It is completely possible to go from a healthy pregnancy to a life-threatening condition in a very short period of time (for me it was about 1 week). I don’t think that women or care givers should go into pregnancy expecting that bad things will happen – but I do think that it’s essential for women to understand the complications that can and do happen.

  5. J. Rose says:

    I disagree with the point that the only possible downside to gestational diabetes is a big baby. GD can also lead to low blood sugar in the newborn, cold stress, mental retardation in some cases and can increase the risk of stillbirth. High blood glucose causes all kinds of problems in the mom’s body that can really hurt the unborn baby if sugars aren’t controlled by diet, exercise, etc. HAVING SAID THAT – I don’t think it’s necessary for everyone to have the 1-hr glucose tolerance test. I am a nurse, I chose a midwife and we have agreed that unless my fasting glucose is high (and I am testing myself at home), there is no reason for me to suffer through drinking syrup and then sitting for an hour. Yuck.

  6. J. Rose says:

    P.S. I enjoyed reading your blog and applaud you for informing women that they DO have choices when it comes to the tests “required” during pregnancy. Thanks!

  7. Julie says:

    I am a nurse-midwife and I whole-heartedly support women’s right to choose the testing and interventions that they will have (or not have) during pregnancy and birth. I figure that if I offer a woman any kind of testing, I ought to be able also to offer a rational reason that makes sense to her.
    I do, however, take issue with your statement that “the only downside of gestational diabetes is that the baby may be big at the time of birth”. Untreated gestational diabetes increases the risk of developing several problems, including blood pressure problems in the mother (which in severe cases may progress to seizures, stroke, or death for mother or baby), babies who are abnormally large (increasing the risk for Cesarean or forceps delivery, birth trauma for mother and/or baby), stillbirth, newborn jaundice, baby’s inability to maintain normal blood sugar, baby’s low blood calcium, or future development of Type 2 diabetes in the baby. That said, if the mother’s abnormal sugar metabolism is diagnosed in a timely fashion, gestational diabetes can be treated with dietary changes that significantly decrease or eliminate these risks for mothers and babies. (Some women will need insulin to keep their blood sugar within normal range).

  8. Tracy says:

    I disagree that testing for gestational diabetes is unnecessary. My mother was diagnosed with gestational diabetes while pregnant with me, in a time when diabetes was not fully understand. She was told not to eat sugar — and that’s it. She gave birth to me, an 11 lb + baby, and has been prediabetic (and now diabetic) since. She was told that if she became pregnant again, she would likely become diabetic immediately (and give birth to another GIANT baby).

    My sister was recently diagnosed with gestational diabetes and is pregnant with her first child. While she has to be careful to monitor her blood sugar frequently, eat very carefully, inject insulin, and exercise often, her chances of being diabetic post-pregnancy are MUCH lower than my mother’s. Her baby will likely be at a normal birth weight, and she can go back to a less rigorous diet after pregnancy and potentially carry other children. If she hadn’t been tested, she wouldn’t have known that she needed to take precautions and it could severely impact her health as well as her child’s.

  9. Kristen says:

    I am pregnant with my first child and have chosen to forego the glucose screening test. After reading how drinking the overtly sugary fluid can have negative affects on one’s body, I chose against it. However, I will say this – I feel 100% comfortable with my decision because I have already been regularly exercising and eating a diet that one would eat if they did have diabetes – eating every few hours and intaking well-balanced foods.
    Since the solution for those who do have GD is to eat right and exercise, there were no changes I would make anyways! So I think if a woman is already doing those things, what’s the point in taking the test?
    Second comment- what do you think about the GBS test? Is it necessary? I’ve been led to believe that it’s a non-negotiable as I would need to have antibiotics during labor if I do have it to protect the baby. Any thoughts?

  10. Kelly Martin says:

    I think there is one more test that is under the optionals, and that would be Strep B. Could you please address this a little bit?

  11. judith lothain says:

    The posts over the last week in response to Charlotte and my writing in The Official Lamaze Guide: Giving Birth with Confidence have demonstrated a keen sense of concern about routine testing during pregnancy (with many women sharing that they refused some testing) and at the same time, some of you comment that it might make good sense to have some of those routine tests.
    Because standard maternity care in the US “looks for trouble” women get put on an assembly line of testing, and are inclined not to question the myriad of tests that providers do routinely. Some do make good sense and are vitally important, like blood pressure checks. Blood pressure checking is not anxiety producing, costly, or time consuming and it is an accurate way to identify a potentially serious problem. Other routine screening tests, like screening for gestational diabetes, are not as straightforward, as many of the comments over the last week have pointed out.
    The back story related to all this testing is RISK. We know that about 14% of women will develop gestational diabetes. We know that the women who do develop gestational diabetes will have increased risks for pre-eclampsia, diabetes in later life, large baby (and all the potential risks that may involve). Although, having gestational diabetes increases the risks of complications, it doesn’t always or even most of the time result in poor outcomes (even if not treated). But, because of these series of increased risks (do you see how complicated it is getting?), pregnant women are routinely screened for gestational diabetes.
    Some women are more at risk for developing gestational diabetes: family history, high BMI, some ethnic groups. It makes sense to watch these women more carefully (keeping in mind they are more at risk but, keep in mind, that doesn’t mean they will actually develop gestational diabetes). Some women without risk factors do develop gestational diabetes. Does that mean every woman should be tested?
    The question of whether all women should be routinely screened (not just those with increased risk or symptoms) is controversial. Check out the Cochrane for a review of the evidence (http://onlinelibrary.wiley.com/o/cochrane/clsysrev/articles/CD007222/frame.html). The Cochrane acknowledges that for women who do have gestational diabetes, treatment (diet, exercise, sometimes insulin) improves outcomes. But, they also conclude that overall routine, universal testing does NOT improve outcomes. And they acknowledge that there is not clear evidence on how best to screen women for gestational diabetes (including at what gestational age testing should be done as well as what specific test is best).
    At the heart of the discussion should be the clear commitment to women’s right to make informed decisions about her care and the care of her unborn baby. In order to make an informed decision women need full information about risks and benefits. Like many of the woman who posted comments this week point out, juggling risk and benefit is sometimes difficult, sometimes not. Just as importantly, women need to spend time thinking about what they will do with the information they receive from a screening test result.
    The two points Charlotte and I wanted to make in the book are that woman do have the right to refuse testing AND that this decision in order to be informed needs to take into account risk (and potential benefit). What is the risk of the test FOR YOU, not for the universe of pregnant women? What is the risk of not doing the test FOR YOU, not for the universe of pregnant women? What is the risk of complications if the test is positive FOR YOU, not for the overall population of women?

  12. Melissa says:

    The very important information that this article is missing: whether or not using these diagnostic tests makes a positive difference. (The author comes closest in the discussion on screening tests for fetal abnormalities.)

    For instance, does being tested and finding out that you have GD lead to treatment that makes you healthier than if you had not been diagnosed? The answer for that one, unfortunately, is no. As a whole, women and their babies do not have better outcomes with testing and treatment, and a simple diagnosis of GD (if you even have it, the tests are non-reproducible and everyone has their own version of what “too high” is) puts you at risk for all sorts of dangerous medical interventions that may not be warranted. Depending on your care provider and chosen birth place, simply having that on your chart might risk you right out of all of the healthy, safe options Lamaze recommends, like being mobile during labor (nope, have to be hooked up to the monitors, flat on your back), letting labor begin on its own (nope, we need to induce you because baby’s going to be SO! BIG! though even ACOG does not recommend induction for this reason, it’s very, very common), or even having a vaginal birth at all. If you have GD, especially if you’re overweight, the pressure or outright manipulation to have a c-section can be overwhelming (some doctors treat such a situation as an automatic c-section, right up there with placenta previa) and that exposes you and your baby to all the risks that such a surgery entails. You may also be forced to rind another provider or move from a homebirth or birth center to a hospital for the birth. Then of course there’s the likelihood that your baby, once born, will be separated from you, repeatedly given heel sticks for glucose checks, given sugar water, denied colostrum, kept in the NICU, etc., all because baby might have a problem with blood sugar levels. Needless to say, this sort of treatment can cause blood sugar problems that may not have otherwise existed.

    The bottom line on GD, it seems, is that the treatment is worse than the disease for most. Can it be serious, even life-threatening? Yes. Of course. But the way we treat it now puts more women and their babies at risk. There has got to be a better way to diagnose when women are having serious blood sugar problems in pregnancy, and a matching treatment protocol that actually improves outcomes.

    As for weight checks: yes, it is helpful. But if women, for any reason, choose not to do weight checks, there are other ways to check for things like edema: how about actually, physically examining the woman? Even my OB checked my ankles for swelling. And weighing someone obsessively at every visit is no substitute for long, detailed talks about how they’re feeling, what they’re eating, what sorts of activities they’re engaged in, etc.

    Even more worrisome than the GD section is this article’s omission of numbers with regard to risk, especially in the section on amniocentesis. The risk of miscarriage—the baby dying–is between one in two hundred and one in four hundred, depending on the source. And, as you point out, that is treated as routine and necessary for such normal, healthy things as simply being over 35. By contrast, the supposedly oh-so-risky VBAC carries with it a 1 in 4,000 risk of death for the baby. I ask you, which one should we be concerned about?

  13. Christine says:

    I refused the glucose test with both my girls. My midwife went over the benefits and drawbacks with me. I had no other signs of gestational diabetes, and there is no diabetes in my family. Why should I have to take a large chunk of time out of my day to go drink a huge amount of sugary gunk, just for them to tell me that my blood sugar level is fine? No thanks :)

  14. VivianT says:

    I had two miscarriages in the past before I finally gave birth from my third pregnancy. They diagnosed the miscarriages from routine first trimester ultrasounds – they found lack of growth and no heartbeat, at weeks 9 and 10, respectively. Other than what was discovered from the ultrasound, there were no other outward signs – no bleeding, cramping or anything. If I did not have the ultrasound, since it is labeled as optional, what other tools/tests would the obstetrician use to determine if there’s been a miscarriage? Particularly during the first trimester?

  15. judith lothian says:

    Vivian, if you had not had the early unltrasounds you and your doctor would have realized you miscarried in all the traditional ways…bleeding, cramping, nausea disappearing. We have always known that if there has been a miscarriage it take days or weeks for bleeding to happen, but it always does. The doctor would then confirm the miscarriage (sometimes there is bleeding with no miscarriage) by a blood test that confirms that hormone levels have changed or by doing an ultrasound. If the ultrasound shows that the uterus has no fetus a d & c is not needed.

  16. Anya Illes says:

    I respect a woman’s right to be informed and to choose which tests and procedures she undergoes. However, I find that the blog post omits many of the benefits of these tests while focusing on the negative. Some of the commenters follow suit. For example, Judith Lothian replied to Vivian T that her “doctor would have realized you miscarried in all the traditional ways.” Well, I have also had an early miscarriage (8.5 weeks) diagnosed by an ultrasound and you know what the BENEFIT of that was? Not waiting. Not continuing on for weeks thinking I was pregnant. Not continuing to stress and worry about the bleeding that came and went. The BENEFIT was that this ultrasound saved me much anxiety and anguish.
    And as for the blog posts comments on testing for genetic disorders – I find the attitude completely irresponsible. I am also at very high risk for passing on a genetic disorder. I think it is irresponsible (even in a blog post) to dismiss the BENEFITS of genetic testing as if they were unimportant. That I “might” want to consider them. Someone like me should ABSOLUTELY at least consider them. It doesn’t mean I should absolutely do the tests, but I should absolutely consider them, for the health and wellbeing of my baby, my family and myself.
    Another example – the accuracy of much of the testing conducted with CVS is actually quite high. The authors use the term “slight risk” when referring to inaccuracies, but go on to still belittle the usefulness of CVS.
    By the way – the genetic counseling that I received was absolutely excellent in explaining the pros and cons, and in explaining the accuracy of the tests that I chose to do. I balk at this blog’s presumption to take on the role of genetic counselor. Those people are very good at their jobs and I respect what they do immensely (I interacted with four different counselors during the course of my pregnancy). When I decided to skip the CVS and/or aminio but do nuchal translucency and blood tests, they were incredibly supportive and respectful of my decisions.

  17. Anya Illes says:

    I also object to the assertion that amniocentesis is viewed as “routine” for women over 35. I also am over 35, and my genetic counselors merely presented me with the pros and cons, and let me make the decision. They merely provided me with the information to consider it. I was never, ever pressured to do it.

  18. judith lothian says:

    Anya, You had excellent counseling related to your options. And your decisions were supported. You are fortunate. Our discussion of prenatal testing, including genetic testing and amniocentesis, is intended to make women aware that these tests are options and should not be routinely done without women’s full understanding and consent. Unfortunately, in some practices, amniocentesis is indeed done routinely, unless women question this. Thank you for sharing your experiences.

  19. HIII says:


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