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Before Birth: Prenatal Screenings Every Mother Should Consider

Posted in: Blogs , English

Pregnancy is a time of great anticipation, and sometimes, great anxiety. It’s easy to become overwhelmed preparing for your baby’s arrival. As the countdown continues and your bump grows, you may wonder whether your baby is developing normally.

While most women have healthy pregnancies, it's important to know your options for obtaining information about your baby's health and development. Women with high-risk pregnancies often need to be closely monitored for potential problems or complications. Fortunately, there are many tests and procedures to monitor the health of both mother and baby throughout the pregnancy.

Here are some of the most common and important prenatal screenings every mother-to-be should consider.

First Trimester Testing

Screenings during the first trimester can detect many things for a soon-to-be mom, including number of babies, gender, anticipated due date, and more. They can also be used to detect abnormalities in the pregnancy. The combination of fetal ultrasound and maternal blood testing can determine the risk of birth defects.

Maternal Blood Testing

The following blood (serum) tests measure two substances found in the blood of all pregnant women. Abnormal levels detected by either test are associated with an increased risk for chromosome abnormality.

Pregnancy-associated plasma protein screening (PAPP-A): A protein produced by the placenta in early pregnancy. 

Human chorionic gonadotropin (hCG): A hormone produced by the placenta in early pregnancy.

Nuchal translucency screening

This screening uses an ultrasound to measure thickness of fluid buildup at the back of the developing baby’s neck.

It is important to remember that these tests, if not done at the right time during your pregnancy, may produce inaccurate results. Additionally, these tests only indicate an increase in risk, which is not a diagnosis.

Second Trimester Testing

Sometimes tests done in the first trimester will be repeated in the second trimester in order to check accuracy, but there will also be new tests during the second trimester that can help mothers be more prepared for the birth of their child.


Depending on the results of the tests performed in the first trimester, amniocentesis can be offered to mothers in order to diagnose chromosomal disorders and open neural tube defects. This type of test is optional and the mother should discuss the risks and benefits with an obstetrician. Amniocentesis is usually offered between weeks 15 and 20.

Glucose Testing

The first step in the glucose testing is a glucose challenge test, which is a one-hour test in order to determine whether the mother is at risk for gestational diabetes. If the initial results are abnormal, a glucose tolerance test is done. Gestational diabetes can cause complications for mothers and babies and should be managed carefully.

Third Trimester Testing

As you grow increasingly excited to meet your baby in the third trimester, it’s important to finish your final set of tests to make sure you can avoid transmitting any infection to the baby during delivery.

Group B Streptococcus Testing

Though you may not know it, you could be a carrier for Group B Strep (GBS), which can be deadly for your baby. The good news is you can significantly decrease the risk if you are treated during labor. About 25 percent of pregnant women test positive for GBS, which are bacteria found in the lower genital tract. Anyone can be a carrier and the origin of GBS is unknown.

A GBS test should be given between weeks 35 and 37 to find out if the mother is a carrier. If the test results are positive, a doctor will deliver antibiotics during labor, which will decrease the risk of mother-to-baby transmission significantly. After GBS is treated in labor, babies have a 1 in 4,000 chance of contracting the disease, as opposed to 1 in 200 prior to treatment.

Remember that a screening test can only provide you with risk, or probability, that a particular condition exists. When the results of a screening test are positive, diagnostic tests can provide a definitive answer. If you are a expectant mother, consult with your Baylor St. Luke’s Medical Group obstetrician to discuss screening options that are right for you and your new baby.



Common Tests During Pregnancy

Maternal and Fetal Testing1st trimester testing

2nd Trimester testing

CDC: About Group B Strep



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