What to expect when you're expecting (25 page)

Couples who know of a hereditary disorder on any branch of either of their family trees. In some cases (as with cystic fibrosis or certain thalassemias), doing DNA testing of the parents before pregnancy makes interpreting later testing of the fetus much easier.

Couples in which one partner has a congenital defect (such as congenital heart disease).

Pregnant women who have had positive screening tests for the presence of a fetal defect.

Closely related couples; the risk of inherited disease in offspring is greatest when parents are related (for example,. in 9 for first cousins).

The best time to see a genetic counselor is before getting pregnant, or in the case of close relatives who intend to start a family, before getting married. A genetic counselor is trained to give couples the odds of their having a healthy child based on their genetic profiles and can guide them in deciding whether or not to have children. But it’s not too late even after pregnancy is confirmed. The counselor can suggest appropriate prenatal testing based on the couple’s genetic profile, and if testing uncovers a serious defect in the fetus, a genetic counselor can outline for the expectant parents all the options available and help them decide how to proceed. Genetic counseling has helped countless high-risk couples avoid the heartbreak of giving birth to children with serious problems, while helping them realize their dreams of having completely healthy babies.

Prenatal Diagnosis

Is it a boy or a girl? Will it have blond hair or brown? Green eyes or blue? Will it have mom’s mouth and dad’s dimples? Dad’s voice and mom’s knack for numbers (or the other way around)?

Babies definitely keep their parents guessing (and placing friendly bets) long before they actually arrive—sometimes before they’re conceived. But the one question that expectant parents wonder about the most is also the one they’re most hesitant to speculate on or even talk about: “Will my baby be healthy?”

Until recently, that question could be answered only at birth. Today, it can be answered as early as the first trimester, through prenatal screening and diagnostic tests. Most expectant
mothers undergo several screening tests during their 40 weeks—even those whose odds of having a baby with a defect are low (because of age, good nutrition, and excellent prenatal care). That’s because such screening tests (from the combined and integrated screenings to the ultrasound and the quad screen) pose no risk to mom or baby but can provide a lot of beneficial reassurance.

Going one step further to definitive diagnostic tests (CVS, amnio, or more detailed ultrasound), however, isn’t for everyone. Many parents—particularly those whose screening tests come back negative—can continue to play the waiting game, with the happy assurance that the chances are overwhelming that their babies are indeed completely healthy. But for those whose concerns represent more than normal expectant-parent jitters, the benefits of prenatal diagnosis can far outweigh the risks. Women who are good candidates for such testing include those who:

Are over 35 (though an older mom with reassuring screening results may decide, after consultation with her practitioner, to skip the diagnostic tests).

Have been exposed since conception to a substance or substances that they fear might have been harmful to their developing baby. (Consultation with a physician can help determine whether prenatal diagnosis is warranted in a particular case.)

Have a family history of genetic disease and/or have been shown to be carriers of such a disease.

Have a genetic disorder themselves (such as cystic fibrosis or congenital heart disease).

Have been exposed to infection (such as rubella or toxoplasmosis) that could cause a birth defect.

Have had pregnancy losses previously, or have had babies with birth defects.