Amniocentesis-related fetal loss: a cohort study.

OBJECTIVE

To assess the risk of fetal loss attributable to second-trimester amniocentesis.

METHODS

A cohort study was undertaken among singleton pregnant women undergoing genetic amniocentesis and controls matched prospectively on a one-to-one basis, matched strictly for maternal age, parity, and socioeconomic status. Both groups were recruited at 15-24 weeks' gestation and observed until delivery. The fetal loss rates of the groups were compared.

RESULTS

A total of 2256 pairs were recruited to the study. After excluding those pairs lost to follow-up, those with fetal malformation, and those later proven to have major chromosomal abnormalities, 2045 matched pairs were compared by pregnancy outcomes. There were no significant differences in fetal loss rates, premature deliveries, or placental abruptions between the study and control groups (P > .05). However, this study did not have enough statistical power to identify differences of less than 1%.

CONCLUSION

Second-trimester amniocentesis is probably not associated with a greater fetal loss rate than that of matched controls.