Risk of low birth weight and preterm delivery in singleton pregnancies conceived by women with and without a history of infertility

Abstract

OBJECTIVE: To determine predictors and risk of low birth weight (LBW) and preterm delivery (PTD) in singleton pregnancies conceived by women with a history of infertility. DESIGN: Retrospective cohort study. MATERIALS AND METHODS: The study was conducted at 11 infertility clinics in Northern California. Data were collected on 983 women who carried singleton pregnancies to ≥ 20 weeks gestation between 1994 and 1998. These women either conceived naturally following a history of infertility or they conceived using infertility treatment. The fertile comparison group (n= 1008) was identified through California Vital Statistics records and matched on singleton status, maternal age, and county of delivery. RESULTS: There was a significant difference in the frequency of LBW between the three groups of women (chi-square 9.12, p=.01). There were more women in the infertile with treatment group compared to the fertile comparison group who delivered a LBW infant. There was no significant difference (chi-square 1.23, p= .541) in the frequency of PTD between the three groups of women. Women with a history of infertility who gave birth to a LBW infant were 1.55 (95% CI 1.03, 2.34) times more likely to have undergone infertility treatment to conceive their pregnancy than those women with a history of infertility who conceived a pregnancy without treatment, controlling for maternal age, parity, gestational diabetes, and obesity. Nulliparity was a significant predictor of LBW; women who gave birth to a LBW infant were 1.51 times (95% CI 1.07, 2.14) more likely to be nulliparous controlling for maternal age, gestational diabetes and obesity, regardless of fertility status. CONCLUSIONS: Women with a history of infertility who undergo infertility treatment and conceive a singleton pregnancy may be at increased risk for giving birth to a LBW infant, but there does not appear to be an increased risk for preterm delivery.