Age-specific risk of fetal loss post second trimester amniocentesis: analysis of 5043 cases

To assess the risk of fetal loss attributable to second trimester amniocentesis in singleton pregnancies through a cross-sectional study.

Records of 5043 consecutive second trimester amniocentesis, performed by a single operator between 1997 and 2003, were analyzed. Fetal loss post amniocentesis was calculated by grouping pregnant women in age classes and assessing observed/expected (O/E) rate.

Total fetal losses were 40 (0.81%): 33 cases (0.67%) occurred before the 24th week, 37 cases (0.76%) before the 28th gestational week, and 3 cases (0.06%) after the 28th week of pregnancy. An age-dependent increase of the rate of fetal loss, not statistically significant (Chi-Square = 0.349, p = 0.505) was observed. The total O/E ratio values did not show any statistically significant risk (O/E ratio = 1.25, CI = 0.86-1.64). The analysis of the single age classes did not detect any statistical significance. The excess fetal loss rate associated with amniocentesis was 0.16%.

No effect of the 2nd trimester amniocentesis was noted on fetal loss.