Assisted reproduction and birth defects

Abstract

Recent publications have indicated the potential for increased birth defect rates in children conceived through assisted reproductive technology (ART). This study was designed to determine the risk of birth defects in ART-conceived children (including IVF, ZIFT, and ICSI) compared to a matched control population. A retrospective cohort study of all children conceived using ART from 1989–2002 through the University of Iowa's Infertility Clinic. Comparison is made with a matched control group of children born in Iowa during that same period. Case children were matched with multiple controls for plurality, maternal age, year of birth, race, and county of delivery. Outcome data was obtained from birth and death certificates, and from the Iowa Birth Defects Registry, an active state-wide surveillance system which audits all Iowa hospitals for birth defects in liveborn and stillborn children through one year of age. Birth defects were classified as major or minor, multiple or isolated, and by organ system as well as individual defect. ART is associated with a small but significant increase in major birth defects in all births and when restricted to singleton births only. Among singletons, birth defect rates are 3.7% for controls and 5.9% for ART (OR 1.62, 95% CI 1.12, 2.34). Multiple gestation is an independent risk factor for major birth defects across all groups. There is no increased risk of multiple (versus isolated) defects between the infertility treatment group and controls. In the ART population, there is a small but significantly increased risk of major birth defects in certain organ systems (cardiovascular, musculoskeletal, and recognized syndromes). Neither ICSI nor cryopreservation confers any additional risk of birth defects or is associated with any specific types of birth defects (e.g., urogenital) as has been noted by previous authors. No significant differences in birth defect rates were noted among the various treatment methods (IVF, GIFT, ZIFT). Singleton ART infants are at increased risk of prematurity and operative deliveries. There is a small but statistically increased risk of major birth defects among children conceived through ART. While we note an increased rate of birth defects, this is not as marked an increase as has been reported in recent, similarly designed studies. ICSI and embryo cryopreservation do not further increase this risk. Birth defect rates in a few specific organ system groups are increased among children conceived through infertility treatments versus controls. Birth defect rates are increased across the various ART procedures suggesting that the increase may be due to some factor in the infertile population rather than the treatments themselves.