Tests You Need During Pregnancy
Prenatal tests are important for your health and your unborn baby's health. Here's what to expect.
These tests are all routine and are performed on every pregnant
woman, Petrikovsky says.
The next set of prenatal tests will be performed between weeks
8-18 of the pregnancy, Petrikovsky says, and will include an ultrasound
screening, which can help determine your due date more accurately, and also
look for abnormalities in the fetus. During this time, your doctor will also
take other blood tests (known as a triple screen or a quad screen) that will
measure blood levels of alpha-fetoprotein, estriol, hCG (human chorionic
gonadotropin), and inhibin, which can indicate whether the fetus is at risk for
abnormalities such as Down syndrome or spina bifida. A newer blood test, PAPPA
(pregnancy-associated plasma protein A), conducted during weeks 10-14 of the
pregnancy and used in conjunction with an ultrasound screening, is a good
choice for women who are at risk of having a baby with a chromosomal
abnormality, says Petrikovsky.
Depending on the results of the blood tests, the age of the
mother (ages 35 and above), or the family history of the mother-to-be, the
doctor may then suggest further prenatal tests, such as chorionic villus
sampling (CVS) or amniocentesis, both of which detect Down syndrome or other
abnormalities. CVS, which is usually done between weeks 10-12 of the pregnancy,
can be performed either by passing a thin tube from the vagina into the cervix
to remove a sample of tissue from the chorionic villi (which makes up the
placenta), or by inserting a needle through the abdominal wall to obtain a
tissue sample. Amniocentesis, which is performed between weeks 16-18 of the
pregnancy, involves the insertion of a needle through the abdominal wall into
the uterus, removing some of the amniotic fluid. Both CVS and amniocentesis
carry a small risk of miscarriage.
Between weeks 24-28, you will be screened again for diabetes
(some women develop pregnancy-related diabetes, known as gestational diabetes,
which usually clears up after the baby is born), and patients who are Rh
negative will be checked for Rh antibodies (which can be treated through a
series of injections), says Petrikovsky.
At the end of the pregnancy, between weeks 32-36, you may be
retested for syphilis and gonorrhea, as well as for group B strep (GBS), a type
of bacterium that can cause meningitis or blood infections in newborn infants;
if you test positive for GBS, you will be given antibiotics during labor and
delivery to minimize the risk of transmitting the bacterium to your infant.
Though these are all routine tests, there may be other prenatal
tests that your obstetrician will recommend, depending on your racial or ethnic
background or family medical history, says Vivian Weinblatt, MS, CGC, regional
manager of genetic services for Genzyme Genetics in Philadelphia and former
president of the National Society of Genetic Counselors.