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 chi2 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.