Pregnancy Outcome Following Second-Trimester Amniocentesis: A Case-Control Study

ABSTRACT The purpose of this study was to investigate whether second-trimester amniocentesis increases fetal loss rate. Two thousand sixty-eight women with singleton gestations who underwent mid-trimester amniocentesis at 15 to 22 weeks gestation and 2068 controls matched one-to-one for maternal age, parity, and the number of prior spontaneous abortions were studied prospectively in a case-control study design. The fetal loss rates and other adverse pregnancy outcomes were compared between the study and control groups using the Pearson χ 2 test or Fisher exact test when appropriate. In the amniocentesis group, eight (0.4%) fetal losses occurred within 30 days of the procedure, and in the control group, six (0.3%) losses occurred within 30 days of the inclusion in the study; the difference was not statistically significant (P = 0.59; OR, 1.34; 95% CI, 0.46 to 3.85). The total fetal loss rates including spontaneous abortions and intrauterine fetal deaths/stillbirths were 2.3 and 2% in the study and control groups, respectively, and the difference was not significant (P = 0.59; OR, 1.12; 95% CI, 0.74 to 1.71). Amniotic fluid leakage occurred in only two (0.1%) of 2068 study patients. Transplacental needle passage was not associated with an increased risk of pregnancy loss compared with nontransplacental amniocentesis (P = 0.92; OR, 0.96; 95% CI, 0.47 to 1.95). There was no statistically significant difference in fetal loss rate between women requiring two needle insertions to obtain amniotic fluid and those having only one insertion (P = 1.00; OR, 0.75; 95% CI, 0.10 to 5.53). The rates of preterm deliveries, small for gestational age infants, preeclampsia/eclampsia, placental abruptions, and cesarean deliveries were also not significantly different between two groups (each P > 0.05). We conclude that second-trimester amniocentesis for prenatal diagnosis is a safe procedure that does not appear to increase fetal loss rate.