When expecting a baby, it’s natural to be concerned about unknown health risks. There are many ways to address these questions, and prenatal testing is one of these ways. Prenatal testing is comprised of a series of special genetic tests that can indicate the presence of genetic abnormalities, or lack thereof.
 

What are the Benefits of Prenatal Testing?

Prenatal testing provides genetic information about the baby while it’s still in the womb. These tests detect health problems in the mother, like gestational diabetes, or fetal abnormalities like spina bifida. In these cases, doctors will administer medical treatment before the baby is born.

These tests also screen for common genetic disorders such as cystic fibrosis, cancer, and Down’s syndrome. If an abnormality is detected, it gives parents more time to prepare and determine the best course of action in handling a child with a birth defect. This includes reviewing treatment and management options for the health condition, reviewing insurance coverage and allocating funds, and other parenting decisions and childcare planning. In this sense, prenatal testing can be a valuable tool in helping expectant parents plan for their future with as much information as possible.
 

Types of Available Prenatal Tests

There are some tests, such as urine analysis and blood pressure checks, that are routine, and therefore are administered at every checkup. But there are also a series of screening tests that are performed during certain trimesters of the pregnancy to test for genetic abnormalities.

Screening tests merely indicate the possible presence of a genetic disorder and do not indicate which disorder is present, or its severity. If the screening test has a positive result, the next step is to perform a diagnostic test to determine which genetic disorder is present.

Many screening tests are non-invasive and some require no more than a blood sample from the mother. Some are packaged together or are offered as a series of tests in a single checkup. These include, but are not limited to:

Glucose Tolerance Test: Tests for gestational diabetes in the mother. She consumes a sugary drink and within an hour her blood is drawn and evaluated on how well her body processes the sugar.

Blood Screening: Tests for the presence of certain substances in the mother’s blood that may indicate genetic disorders, such as Down’s syndrome or cystic fibrosis.

Prenatal Cell-Free DNA Testing: Evaluates fetal DNA in the mother’s bloodstream for certain chromosome conditions and to reveal the sex of the fetus.

Ultrasound: Using sound waves and a digital screen, the doctor can visually inspect the fetus and placenta for physical abnormalities, as well as determine the fetus’ age.

Non-Stress Test: Movement and heart rate of the fetus are monitored using special belts attached to the mother’s abdomen.

Additional diagnostic tests may require pelvic exams or other fluid samples to determine if the fetus has a genetic condition. These tests carry a low risk of miscarriage and include, but are not limited to:

Chorionic Villus Sampling (CVS) : Sampling of the placenta

Amniocentesis : Sampling of the amniotic fluid

In the event that both parents carry a gene that makes the fetus predisposed to a genetic disorder, certain tests are more likely to be administered.

While prenatal testing can help assess many types of disease early so that parents can take action accordingly, there are some illnesses and conditions for which there are no tests. But for many, knowing as much as possible is an important step in preparing for parenthood.

By Dr. Rasik Rangsiprakarn , Gynecologist and Obstetrician, Women’s Center, Bumrungrad Hospital

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