Pregnant? Here are Prenatal Tests and Screenings to Expect

By Karen B. Simon, M.D.

When you get pregnant, you’ll likely already be familiar with some of the tests your doctors will perform over the next nine months. However, there are quite a few you may not have heard of before. But no need to worry; just like the ultrasounds you’re looking forward to, these tests and screenings help ensure you and your baby are both healthy.

Here are some of the tests you can expect.

Blood Testing

At your very first prenatal visit, you’ll likely be asked to provide your doctor with a blood sample, which will be tested for conditions, diseases, and immunities that could impact your pregnancy and delivery. Your doctor will also check your blood type and Rh factor, which is a protein carried by red blood cells in some people and not others. If you have the protein, you’re Rh positive but if you don’t, you’re Rh negative – in this case, you’ll need a simple treatment to protect you and your baby during your pregnancy.

Urine Testing

Make sure you stay hydrated, and drink plenty of water before your prenatal visits, because you’ll most likely be providing your doctor with a urine sample at each appointment. A urinalysis checks for potentially dangerous pregnancy complications including high blood pressure, or preeclampsia, and gestational diabetes. Both are treatable if they’re identified.

Level II Ultrasound

Also sometimes referred to as an anatomy scan, this exam is typically done between 18 and 20 weeks of pregnancy. This painless, non-invasive test is a detailed examination of your baby’s anatomy to ensure that each part of the body has formed properly, and that he or she is growing and developing as expected. This ultrasound can help confirm your due date, whether you’re having twins, and if you’re having a boy or a girl.

Sequential Screening

This test involves an ultrasound around 12 weeks along, which will measure the thickness of the nuchal fold, which is located in the back of the baby’s neck. This fold may be too thick in babies with certain problems. A blood sample from mom will be taken at 12 weeks and again at 16 weeks. The results from the nuchal measurement and the blood tests will be used to calculate whether the baby has an increased risk for certain genetic disorders such as Down syndrome. This test does not give a definite “yes” or “no”; rather, it only indicates if the baby should undergo further evaluation with other tests such as the ones listed below.


The amniotic fluid surrounding your fetus contains fetal cells, chemicals and microorganisms that can provide your doctor with a wide range of information about your baby. With an amniocentesis, a needle is used to extract a small amount of amniotic fluid to evaluate fetal genetic information. This test is ultimately a prenatal diagnostic tool for chromosomal abnormalities such as Down syndrome, genetic diseases like Tay-Sachs, and neural tube defects like spina bifida. It can be performed as early as 15 weeks gestation and right up to delivery.

Chorionic Villus Sampling (CVS)

Similar to an amniocentesis, CVS evaluates fetal cells for genetic disease. With this test, a small tissue sample is taken from the placenta, which contains the same genetic information as your baby – it’s used to rule out chromosomal disorders. CVS is performed at the end of the first trimester, and thus provides detailed genetic information earlier than an amniocentesis.

Non-Invasive Prenatal Testing

This new test obtains a blood sample from mom, and can evaluate the baby’s genetic makeup in order to test for Down Syndrome and other genetic disorders.  This test is offered to women age 35 and over and couples with a family or personal history of certain genetic disorders.

Fetal Echocardiogram

If your baby is at risk of genetic heart defects, this test will allow a doctor to perform a detailed exam of your baby’s heart.

Fetal Fibronectin Testing

In the event that you’re identified as having a high risk of delivering preterm, this non-invasive test will measure the fetal fibronectin, which holds the baby in the womb.  This test is used to determine if a woman is at high risk for preterm delivery in the near future.

Genetic Counseling

There are a number of reasons pregnant couples may be referred to a genetic counselor:

  • The mother will be 35 or older at her due date
  • Someone in mom or dad’s family has a genetic condition or birth defect
  • You were exposed to certain infections, radiation, forms of medication, or a chemical agent
  • You’re of an ethnic background that puts your baby at risk for a genetically-inherited disease
  • Abnormal test results on a genetic screening test
  • In genetic counseling, a counselor will help you determine if your baby is at risk for a birth defect or genetic disease in addition to explaining your choices if a concern is found and answer your questions.

Diabetes Screening

All women will be checked late in the second trimester to be sure they are not developing diabetes caused by the pregnancy, called gestational diabetes.

Group B Strep Testing

Up to one-third of women carry a bacteria in the vagina called “group B strep.” This bacteria is normal to have and is not sexually transmitted. All women will be screened for group B strep about a month before the due date. Women who are found to carry it are given an antibiotic during labor to protect the baby.

About the Author

Karen B. Simon, M.D.

Dr. Simon specializes in Obstetrics and Gynecology (OB/GYN). She attempts to help patients become educated about their health and treatment options before they make decisions together.

To schedule an appointment with Dr. Simon, please call 610-872-7660.

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