Infertility treatment and risk of severe maternal morbidity: a propensity score-matched cohort study

BACKGROUND: The extent to which infertility treatment predicts severe maternal morbidity is not well known. We examined the association between infertility treatment and severe maternal morbidity in pregnancy and the postpartum period. METHODS: We conducted a cohort study using population-based registries from Ontario between 2006 and 2012. Pregnancies achieved using infertility treatment (ovulation induction, intrauterine insemination or in vitro fertilization with or without intracytoplasmic sperm injection) were compared with unassisted pregnancies using propensity score matching, based on demographic, reproductive and obstetric factors. The primary outcome was a validated composite of severe maternal morbidity or maternal death from 20 weeks' gestation to 42 days postpartum. We also calculated the odds ratio of a woman having 1, 2, or 3 or more severe maternal morbidity indicators in relation to invasive (e.g., in vitro fertilization) or noninvasive (e.g., intrauterine insemination) infertility treatment. RESULTS: We matched 11 546 infertility treatment pregnancies with 47 553 untreated pregnancies. Severe maternal morbidity or maternal death occurred in 356 infertility-treated pregnancies (30.8 per 1000 deliveries) versus 1054 untreated pregnancies (22.2 per 1000 deliveries); relative risk 1.39 (95% confidence interval [CI] 1.23-1.56). The likelihood of a woman having 3 or more severe maternal morbidity indicators was increased in women who received invasive infertility treatment (odds ratio [OR] 2.28, 95% CI 1.56-3.33) but not in those who received noninvasive infertility treatment (OR 0.99, 95% CI 0.57-1.72). INTERPRETATION: Women who undergo infertility treatment, particularly in vitro fertilization, are at somewhat higher risk of severe maternal morbidity or death. Efforts are needed to identify patient- and treatment-specific predictors of severe maternal morbidity that may influence the type of treatment a woman is offered.