Obstetric consequences of subfertility: a retrospective cohort study

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=52443, twin=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 preeclampsia, 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 and delivering a singleton were at a higher risk of pre-eclampsia (adjusted risk ratios and 95% confidence intervals) (1.18, 1.02-1.37), antepartum haemorrhage (1.32, 1.18- 1.47), induction of labour (1.21, 1.11-1.31) and very preterm delivery (<32 weeks) (1.96, 1.53- 2.49). Subfertile women delivering twins were at a higher risk of being delivered by emergency caesarean section (2.14, 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.