Perinatal outcome among singleton infants conceived through assisted reproductive technology in the United States

OBJECTIVE: To examine perinatal outcome among singleton infants conceived with assisted reproductive technology (ART) in the United States. METHODS: Subjects were 62,551 infants born after ART treatments performed in 1996-2000. Secular trends in low birth weight (LBW), very low birth weight (VLBW), preterm delivery, preterm LBW, and term LBW were examined. Detailed analyses were performed for 6,377 infants conceived in 2000. Observed numbers were compared with expected using a reference population from the 2000 U.S. natality file. Adjusted risk ratios were calculated. RESULTS: The proportion of ART singletons born LBW, VLBW, and term LBW decreased from 1996 to 2000. The proportion delivered preterm and preterm LBW remained stable. After adjustment for maternal age, parity, and race/ethnicity, singleton infants born after ART in 2000 had elevated risks for all outcomes in comparison with the general population of U.S. singletons: LBW standardized risk ratio 1.62 (95% confidence interval 1.49, 1.75), VLBW 1.79 (1.45, 2.12), preterm delivery 1.41 (1.32, 1.51), preterm LBW 1.74 (1.57, 1.90), and term LBW 1.39 (1.19, 1.59). Risk ratios for each outcome remained elevated after restriction to pregnancies with only 1 fetal heart or any of 7 other categories: parental infertility diagnosis of male factor, infertility diagnosis of tubal factor, conception using in vitro fertilization without intracytoplasmic sperm injection or assisted hatching, conception with intracytoplasmic sperm injection, conception in a treatment with extra embryos available, embryo culture for 3 days, and embryo culture for 5 days. CONCLUSION: Singletons born after ART remain at increased risk for adverse perinatal outcomes; however, risk for term LBW declined from 1996 to 2000, whereas preterm LBW was stable. LEVEL OF EVIDENCE: III