Risk for fetal loss and prematurity after 12,413 second trimester amniocenteses in a single center

The purpose of this retrospective controlled study is to estimate the risk for fetal loss and preterm delivery attributed to second trimester amniocentesis from a single tertiary center.

The study group consists of 12,413 singleton pregnancies with consecutive amniocenteses, performed in a single tertiary center during a 15-year period (1996-2010) with known pregnancy outcome. The control group consisted of 6993 pregnancies with negative second trimester screening for aneuploidies during the same period who did not have any invasive test. The two groups were compared in terms of fetal loss rate up to 24 weeks and premature deliveries.

Total fetal loss up to 24 weeks in the study group, excluding terminations of pregnancy, was estimated at 1.25% (1.05%-1.45%, confidence interval [CI]: 95%). In the control group the loss rate was 0.65% giving a procedure related fetal loss rate of 0.6% which was not found to be a statistically significant difference. Delivery before the 28th, 32nd, 34th, and 37th week in the study group was reported in 0.2%, 0.8%, 1.2% and 8.1% respectively, and it was not statistically different from controls.

The present study has shown that the risk of miscarriage that can be attributed to amniocentesis in our institution is 0.6%, and this is not statistically significant when compared with cases without any invasive procedure during pregnancy. Similarly, the risk for preterm labor was not statistically significant when compared with controls.