Infant morbidity following amniocentesis and chorionic villus sampling for prenatal karyotyping.

OBJECTIVE To investigate whether amniocentesis and chorionic villus sampling increase the risk of postural deformities, limb reduction defects, respiratory problems in the newborn, fetal and infant mortality, prematurity, low birthweight and fetal distress, and to investigate the impact of gestational length at the time of the procedure. DESIGN A population-based cohort study. SETTING Sweden, 1991-1996. POPULATION All women, 35 to 49 years old, with single births (n= 71,586). The women were classified as exposed to amniocentesis (n= 21,748) or chorionic villus sampling (n= 1984) or not exposed (n= 47,854). METHODS Infant outcomes were collected from the Swedish Medical Birth Register, the Swedish Hospital Discharge Register, the Swedish Malformation Register and the Swedish Cause of Death Register. Odds ratios were calculated with logistic regression analyses. MAIN OUTCOME MEASURES Crude and adjusted odds ratios of postural deformities, limb reduction defects, respiratory problems in the newborn, fetal and infant mortality, prematurity, low birthweight and fetal distress. Women exposed to amniocentesis or chorionic villus sampling were compared with non-exposed women. RESULTS An increased risk of musculoskeletal deformities (OR = 1.32, 95% CI 1.11-1.57) including club foot and hip dislocation was found in the amniocentesis group, especially for amniocentesis prior to 14 weeks of gestation. Respiratory disturbances such as neonatal pneumonia, meconium aspiration, atelectasis and tachypnea were found more often in the amniocentesis group (OR = 1.12, 95% CI 1.02-1.24), with the greatest risk at 14 and 15 weeks of gestation. For the chorionic villus sampling group, no significant associations were found. No increase regarding limb reduction defects, fetal and infant mortality, prematurity, low birthweight and fetal distress was found in either the amniocentesis or the chorionic villus sampling group. CONCLUSIONS Among women aged 35-49 years, amniocentesis before 14 weeks of gestation increases the risk of postural deformities. Amniocentesis at 14 and 15 weeks increases the risk of respiratory disturbances. For chorionic villus sampling, a larger study group is needed before such risks can be ruled out.