Assisted reproductive technology and the risk of preterm birth among primiparas.

OBJECTIVE: To investigate the risk of preterm birth among liveborn singletons to primiparas who conceived with assisted reproductive technology (ART) using four mutually exclusive categories of infertility (female infertility only, male infertility only, female and male infertility, and unexplained infertility) and to examine preterm birth risk along the gestational age continuum.

DESIGN: Retrospective cohort study.

SETTING: Not applicable.

PATIENT(S): Singletons born to primiparas who conceived with or without ART.

INTERVENTION(S): None.

MAIN OUTCOME MEASURE(S): Preterm (<37 weeks' gestation) and preterm/early term birth <39 weeks' gestation).

RESULT(S): For the male infertility only, female infertility only, combined male and female infertility, and unexplained infertility groups, ART-conceived singletons were significantly more likely than non-ART singletons to be born preterm: adjusted odds ratio (aOR) 1.24 (95% CI, 1.13, 1.37), aOR 1.60 (95% CI, 1.50, 1.70), aOR 1.49 (95% CI, 1.35, 1.64), and aOR 1.26 (1.12, 1.43) respectively. Among infants whose mothers were diagnosed with infertility, the odds of preterm birth were highest between 28-30 weeks [female infertility only, aOR 1.95 (95% CI, 1.59, 2.39); male and female infertility: 2.21 (95% CI, 1.62, 3.00)] compared with infants in the general population. Within the ART population, singletons of couples with female infertility only were more likely to be born preterm than singletons born to couples with other infertility diagnoses.

CONCLUSION(S): Among singleton births to primiparas, those conceived with ART had an increased risk for preterm birth, even when only the male partner had been diagnosed with infertility. The risk of preterm birth for ART-conceived infants whose mothers were diagnosed with infertility included the earliest deliveries.