Trying to get pregnant? Make sure you know the bottom line on baby-making—what you don't understand can affect your bub-to-be's health.
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By her second trimester, Elizabeth Lampert, then 34, was used to the seemingly endless prenatal tests. So when her obstetrician drew blood for a routine procedure called a maternal serum screening (also known as a double marker, triple marker or alphafetoprotein [AFP] test), Lampert didn’t think twice. Until she got the results, that is: The test indicated that her baby might have Down syndrome or another defect. “I was just destroyed,” she recalls.
Lampert later learned that maternal serum screening is notoriously inaccurate. Her test result, like those of approximately 124,000 of the 2.1 million American women who take the test each year, turned out to be a “false-positive,” suggesting a problem when there wasn’t one (2,000 are true positives).
While the purpose of the test is to identify babies who might have certain genetic or developmental defects, including Down syndrome and spina bifida, the only way to find out for sure is through another test, usually amniocentesis. Lampert had another maternal serum screening and an ultrasound (she chose not to undergo amniocentesis) before learning her baby was fine. Although relieved after weeks of anxiety, she was left shaken and angry.
Although there are no official figures, a small but determined number of women are opting out of at least some routine prenatal tests. For example, Wendy R. Hurst, M.D., a New Jersey obstetrician-gynecologist, estimates that 2 percent of her patients refuse procedures like maternal serum screening and amniocentesis.
Still, some medical professionals are troubled. “Our fear is that women are turned off by the process,” says Jacob Canick, Ph.D., director of the division of prenatal and special testing at Women & Infants Hospital in Providence, R.I. Canick’s research has found that women who get positive maternal serum screening results in their first pregnancy are less likely to agree to the test during a subsequent one. This may lead to some medical complications going undetected until the baby is born.
But these maverick moms-to-be have reasons for just saying no that even doctors concede are valid. Some worry about harming their babies. Most tests, including maternal serum screening, are risk-free; but invasive procedures like amniocentesis and chorionic villus sampling (CVS) — the only two that can definitively diagnose genetic defects — are not. In one of every 200 to 400 women who undergo amniocentesis, for example, the procedure results in miscarriage, according to the Centers for Disease Control and Prevention. Some women, particularly those who have had miscarriages or struggled to get pregnant, don’t want to take even the slightest chance.