Effects of in vitro fertilization on low birth weight, preterm delivery, and multiple birth.

PURPOSE: To quantify the contribution of in vitro fertilization (IVF) on changes in the rates of low birth weight (LBW), preterm delivery, very low birth weight, and multiple births during the past 3 years.

METHODS: Data on IVF pregnancies from 1994 to 1996 within Alberta were reviewed. Population data were obtained from the Provincial notice of a live or stillbirth.

RESULTS: The IVF component of increased LBW rate in the province was 17.8% for infants <2500 g and 43.5% for those born <1500 g. IVF accounted for 10.5% of the provincial rate increase in deliveries <37 weeks' gestation and 66.2% of those <30 weeks' gestation. IVF accounted for 21.4% of the twins and all of the sets of triplets in the province.

CONCLUSION: During a 3-year period IVF has affected the incidence of LBW, preterm delivery, and multiple birth. IVF is a substantial contributor to changes in very low birth weight and delivery before 30 weeks, which is partly related to multiple births.