Infant Morbidity Following Amniocentesis and Chorionic Villus Sampling for Prenatal Karyotyping

Abstract

Although invasive methods, including amniocentesis and chorionic villus sampling, are now an established part of obstetric care and are offered for low-risk indications, the extent of risk to the fetus and infant-if any-is not clear. Both miscarriages and major orthopedic postural abnormalities have been ascribed to these procedures. All women 35 to 49 years of age who had a single birth in Sweden in the years 1991 to 1996 were included in this population-based cohort study. The total group of 71,586 mothers included 21,748 women having amniocentesis, 1984 having chorionic villus sampling, and 47,854 having neither of these procedures. Amniocentesis typically was done at 13 to 16 weeks gestation and chorionic villus sampling at 10 to 12 weeks. Compared with nonexposed women, those having amniocentesis were at increased risk of musculoskeletal malformations (odds ratio [OR], 1.32; 95% confidence interval [CI], 1.11-1.57). The risk was significantly increased only when amniocentesis was done earlier than 14 weeks gestation. Amniocentesis also increased the risk of club foot (OR, 1.45; 95% CI, 1.06-1.99) and hip dislocation (OR, 1.22; 95% CI, 0.99-1.5). Although the numbers were low, women in the amniocentesis group had elevated risks of congenital arthrogryposis, curving of the leg bones, and knee dislocation. Musculoskeletal malformations did not appear to be increased by chorionic villus sampling. Limb reduction defects were similarly frequent in all 3 groups. Respiratory disturbances were more prevalent in infants whose mothers underwent amniocentesis (OR, 1.12; 95% CI, 1.02-1.24), especially when the procedure was done at 14 to 15 weeks gestation. Neonatal pneumonia also was more prevalent after amniocentesis (OR, 1.29; 95% CI, 1.02-1.65). Meconium aspiration was more frequent, but only with amniocentesis done at 13 weeks gestation (OR, 1.77; 95% CI, 1.06-2.93). Neonatal pneumonia did not correlate with either meconium aspiration or chorioamnionitis. In women having chorionic villus sampling, OR values were at approximately the same level above unity but the differences were not statistically significant. Neither procedure was associated with low 5-minute Apgar scores. Preterm births were less frequent in women having one of the invasive procedures. Fetal deaths were less frequent in the chorionic villus sampling group than in nonexposed women. None of the observed effects were modified when taking age into account. The central findings in this large cohort study of women aged 35 to 49 years were that the risk of postural deformities is increased when amniocentesis is done earlier than 14 weeks gestation, and that the risk of respiratory disorders is elevated after amniocentesis at 14 and 15 weeks gestation.