Obstetric consequences of subfertility: a retrospective cohort study

Abstract

Objective: To compare the risk of adverse pregnancy outcomes in women with and without subfertility and to investigate whether fertility treatment contributes to the adverse outcomes. Design: Register-based retrospective cohort study. Setting: Aberdeen, Scotland. Population: The exposed group included women with subfertility attending Aberdeen Fertility Clinic between 1989 and 2008 and delivering a singleton (n = 3188) or twin (n = 350) at Aberdeen Maternity Hospital between 1992 and 2009. The unexposed cohort included the remainder of women (singleton n = 52443, twin n = 1125) delivering at Aberdeen Maternity Hospital between 1992 and 2009. Methods: The Aberdeen Fertility Centre database and Aberdeen Maternity and Neonatal Databank were linked using Community Health Index numbers. Regression models were used to calculate risk ratios and 95% confidence intervals adjusting for potential confounders. Main outcome measures: Maternal outcomes including pre-eclampsia, antepartum haemorrhage, preterm birth, induction of labour; delivery outcomes including operative vaginal delivery, caesarean section; and offspring outcomes including low birthweight, stillbirth and neonatal death. Results: Women with a history of subfertility who delivered a singleton were at a higher risk of pre-eclampsia [adjusted risk ratios (aRR) 1.18, 95% confidence intervals (CI) 1.02–1.37], antepartum haemorrhage (aRR 1.32, 95% CI 1.18–1.47), induction of labour (aRR 1.21, 95% CI 1.11–1.31) and very preterm delivery (<32 weeks) (aRR 1.96, 95% CI 1.53–2.49). Subfertile women delivering twins were at a higher risk of being delivered by emergency caesarean section (aRR 2.14, 95% CI 1.26–3.66). There were no significant differences in adverse outcomes for singleton pregnancies between the treated and untreated subfertile couples. Conclusion: Subfertility per se, rather than fertility treatment, was associated with increased risk of adverse outcomes in singleton pregnancies. Tweetable abstract: Large cohort study found higher incidence of adverse outcome in subfertile women having singletons or twins.