What Are the Risks?
CVS has been studied extensively in medical centers in the United States and throughout the world. The risks include:
- leakage of amniotic fluid
- a low chance of infection
- miscarriage (0.5-1.0%)
There had been some controversy over the possible association of limb defects and CVS procedures, especially when the CVS was performed prior to the fetus being 10 weeks old. Several recent studies have found that the incidence of limb defects is no greater than that in the general population as long as the CVS is performed at 10 weeks gestation or more. (ACOG Practice Bulletin, No. 27, May 2001) There is always a risk of miscarriage in any pregnancy. On average, about one in every 20 pregnancies (4.7%) will end in miscarriage by the 12th week of gestation. Miscarriage rates vary with past pregnancy history, medical conditions and the age of the mother. For example, among mothers 35 years of age and older, the rate of miscarriage increases to 8.7% by the 12th week of gestation. Since CVS is an invasive procedure, there is a small increase in the risk for miscarriage above this background risk.