Early amniocentesis and congenital foot deformities

Objective: Several studies have shown an increased risk of congenital foot derformities after early amniocentesis. These studies have comprised amniocenteses performed before 13 completed gestational weeks. In this study, the risk of foot deformities after amniocentesis performed at 12-14 completed gestational weeks was determined. Methods: 3,469 genetic amniocenteses in singleton pregnancies performed before 15 completed gestational weeks were studied. The intention was to perform the amniocenteses at 12-14 weeks of gestation, but 32 amniocenteses were performed at the gestational age 11 weeks + 5 days or 11 weeks + 6 days. The pregnancies were followed up with regard to fetal loss and leakage of amniotic fluid. After birth, newborns with a diagnosis of foot deformity were identified from the Swedish Medical Birth Registry. The observed number of foot deformities was then compared with the expected number which was calculated stratified for delivery hospital, year of birth, and maternal age. Results: The observed number of foot deformities was significantly higher than the expected: exact odds ratio 1.74 (exact 95% confidence interval 1.06-2.69). The rate of spontaneous abortions after the procedure was 1.8%, and the rate of leakage of amniotic fluid was 1.9%. There was a significant trend for all complications to decrease with increasing gestational age at amniocentesis. Conclusion: Women undergoing amniocentesis at 11 + 5 to 14 + 6 gestational weeks have an increased risk of giving birth to a child with a congenital foot deformity.