Common Prenatal Tests: Ensuring the Health of Mother & Baby During Pregnancy | Ankura

Welcome to the important topic of prenatal genetic testing, an essential aspect of contemporary pregnancy care. The path to parenthood is often filled with both excitement and anxiety, particularly when considering the health of your unborn child. This blog is here to guide you, offering valuable information on the reasons behind these screenings. 

Prenatal tests are medical tests you get during pregnancy. They help your health care provider find out how you and your baby are doing.

You get some prenatal tests several times during pregnancy at your prenatal care checkups. These tests make sure you and your baby are staying healthy. There are other tests that are done at certain times during your pregnancy. These prenatal tests check to see if your baby has any health problems, including:

Birth defects-These are health conditions that are present at birth. They change the shape or function of one or more parts of the body. Birth defects can cause problems in overall health, how the body develops or how the body works.

Genetic and chromosomal conditions- These conditions are caused by changes in genes and chromosomes. A gene is part of your body’s cells that stores instructions for the way your body grows and works. A chromosome is the structure in cells that holds genes. Genetic conditions include cystic fibrosis (also called CF), sickle cell disease and heart defects. A common chromosomal condition is Down syndrome. Sometimes these conditions are passed from parent to child, and sometimes they happen on their own.

If there is a history of certain health conditions in your family, you may want to talk with a genetic counselor. A genetic counselor has training to help you understand about birth defects and other medical conditions that run in families and how they can affect your health and your baby’s health.

The Importance of Prenatal Care

Prenatal care is crucial for ensuring a healthy pregnancy and the well-being of both the mother and baby. Regular pregnancy health checks allow healthcare providers to monitor the progress of the pregnancy and address any potential complications early. These visits typically include physical exams, blood tests, and ultrasounds to assess the mother’s health and the development of the fetus. Early detection of any health concerns is vital in preventing or managing conditions that could affect the pregnancy, such as gestational diabetes, high blood pressure, or fetal growth issues.

Monitoring fetal health is one of the primary focuses of prenatal care. Through various tests, including ultrasounds and blood screenings, doctors can evaluate the baby’s development and identify potential risks or birth defects. For instance, first-trimester screenings, such as nuchal translucency ultrasounds and maternal serum tests, help assess the risk of chromosomal abnormalities like Down syndrome. Later in pregnancy, an anatomy scan provides a detailed look at the baby’s organs and growth, while glucose screening tests check for gestational diabetes.

In addition to ensuring fetal well-being, prenatal testing also offers an opportunity for expectant parents to ask questions and prepare for labor and delivery. It provides peace of mind, knowing that any health issues can be addressed in a timely manner. Ultimately, prenatal care and testing serve as a safeguard, ensuring both the mother and baby are supported throughout the pregnancy, leading to the best possible outcomes.

Knowing the distinction between screening and diagnostic testing is crucial. Screening tests determine a baby’s risk of developing a certain health condition, but they don’t offer a definitive response. Routine screening tests, such as combined first-trimester screening, maternal serum screening in the second trimester, and non-invasive prenatal testing (NIPT, also called cell-free DNA screening), for instance, can provide estimates of a condition’s likelihood, such as one in 1,000.

Diagnostic testing, on the other hand, provides more conclusive findings. Diagnostic tests that can determine if a baby has a certain problem include amniocentesis, chorionic villus sampling (CVS), and ultrasound.

First trimester screening involves a combination of fetal ultrasound and maternal blood tests to assess the risk of certain birth defects in the fetus. This screening may be used alone or alongside other tests.

First trimester screenings include:

Ultrasound for fetal nuchal translucency: This ultrasound examines the back of the fetal neck for excess fluid or thickening, which can indicate an increased risk for chromosomal abnormalities.

Ultrasound for fetal nasal bone determination: An ultrasound between 11- and 13-weeks gestation checks for the presence of the nasal bone, which may not be visible in some babies with certain chromosomal abnormalities like Down syndrome.

Maternal blood tests: These tests measure two substances found in all pregnant women’s blood:

Pregnancy-associated plasma protein A (PAPP-A): A protein produced by the placenta early in pregnancy, with abnormal levels indicating a higher risk for chromosomal abnormalities.

Human chorionic gonadotropin (hCG): A hormone produced by the placenta early in pregnancy, with abnormal levels linked to a higher risk for chromosomal abnormalities.

When combined, these tests are more effective in determining if the fetus may have a birth defect, such as Down syndrome (trisomy 21) or trisomy 18. If the screening results are abnormal, genetic counselling is recommended, and additional tests like chorionic villus sampling (CVS), amniocentesis, or cell-free fetal DNA may be necessary for a definitive diagnosis.

In the second trimester (months 4, 5, and 6 of pregnancy), your healthcare provider may offer additional prenatal tests:

Maternal blood screening (quad screen): This test checks for an increased risk of certain birth defects like Down syndrome by measuring four substances in the blood: alpha-fetoprotein (AFP), estriol, human chorionic gonadotropin (hCG), and inhibin A. This test is typically done between 15 and 22 weeks of pregnancy.

Ultrasound: Performed between 18 and 22 weeks, this ultrasound examines the baby’s growth, development, and checks for any birth defects.

Amniocentesis: A sample of amniotic fluid is taken to test for genetic conditions or birth defects. It is usually performed between 15 and 20 weeks, especially if you’re over 35, have a family history of genetic disorders, or if the first trimester screening indicated an increased risk.

Glucose screening: Done between 24 and 28 weeks, this test checks for gestational diabetes, a type of diabetes that develops during pregnancy.

In the third trimester (months 7, 8, and 9), one important test is: Group B Strep (GBS) test: This test checks for the presence of group B strep, a bacteria that can be passed to the baby during birth. The test is performed between 35 and 37 weeks of pregnancy by checking a sample of fluid from the cervix.

Ultrasounds are typically performed at different stages of pregnancy for various purposes:

Prenatal testing can be very important because it will provide you with the information through a simple blood test that may help assess the risk of early delivery for each pregnancy. It means your doctor will be in a better position to give the necessary support, according to your pregnancy. Results from this test enable you and your doctor to take proactive measures that will ensure an extension of pregnancy, improved fitness, improved diet, and potentially shorter stay in the hospital and a higher possibility of having a healthy baby.