Low-technology assisted reproduction and the risk of preterm birth in a hospital-based cohort

Objective: To estimate the risk of preterm birth in singleton infants conceived through low-technology assisted reproduction (intrauterine insemination and/or ovulation induction/stimulation). Design: Hospital-based cohort study. Setting: University-affiliated hospital. Patient(s): Singleton babies born between 2001 and 2007 to 16,712 couples with no reported infertility (reference category), 378 babies conceived with low-technology treatment; 437 conceived with high-technology treatment; and 620 conceived naturally after a period of infertility. Intervention(s): None. Treatment data were obtained from couples undergoing standard infertility investigation and care. Main Outcome Measure(s): Preterm birth, defined at three clinical endpoints: <37, <35, and <32 weeks of completed gestation. Result(s): After adjustment for age, parity, education, smoking, alcohol/drug use, and body mass index, the risk ratios and 95% confidence intervals (CI) of preterm birth for low technology were: 1.49 (CI: 1.12-2.00); 2.02 (CI: 1.30-3.13); and 2.93 (CI: 1.63-5.26) at <37, <35, and <32 weeks gestation, respectively, not dissimilar from the estimates for in vitro fertilization. Restricting the analysis to primiparas strengthened the association between treatment and preterm birth at the lower gestational endpoints. The increased risk persisted when the untreated group was used as the reference category, although the estimates were attenuated. Conclusion(s): In this large hospital-based cohort study, low-technology assisted reproduction appeared to be a moderately strong predictor of preterm birth, with similar associations observed in the high-technology treatment group. After adjusting for confounders, as well as the shared characteristics of infertile couples, associations were attenuated but remained significant, suggesting that part of the risk is likely attributable to the treatment. (C) 2015 by American Society for Reproductive Medicine.