The effect of method and gestational age at termination of pregnancy on future obstetric and perinatal outcomes: a register-based cohort study in Aberdeen, Scotland

Objective: To determine whether termination of pregnancy (TOP), including the method used or gestational age at termination, affects future obstetric and perinatal outcomes.

Design: Register-based cohort.

Setting: Aberdeen Maternity Hospital, Scotland, UK.

Population: From the Aberdeen Maternity and Neonatal Databank (AMND) we identified 3186 women who had terminated their first pregnancy and then had a second pregnancy of beyond 24 weeks of gestation between 1986 and 2010. We identified 42,446 women who had their first delivery in the same time period, for comparison.

Methods: Univariate and multivariate logistic regression was used to compare outcomes between groups. Complete case analysis with adjustment of confounding factors was carried out, and adjusted odds ratios (aORs) with 99% confidence intervals are presented.

Main outcome measures: The primary outcome was spontaneous preterm delivery (SPTD).

Results: No statistically significant association was found between TOP in the first pregnancy and SPTD in the next pregnancy (aOR 1.05; 99% CI 0.83-1.32). Neither medical (aOR 1.03; 99% CI 0.72-1.46) nor surgical (aOR 1.06; 99% CI 0.78-1.44) termination appeared to affect the risk of spontaneous preterm delivery in the subsequent pregnancy. Late termination (≥13 weeks of gestation) did not appear to increase the risk of spontaneous preterm delivery compared with early termination (<13 weeks of gestation) (aOR 1.65; 99% CI 0.94-2.92), nor compared with primigravid women (aOR 1.25; 99% CI 0.97-1.62). There was an associated increased risk of antepartum haemorrhage in the next pregnancy following TOP (P < 0.01; aOR 1.26; 99% CI 1.10-1.45).

Conclusions: Evidence on obstetric and perinatal outcomes following TOP remains conflicting. This study suggests that TOP is not associated with an increased risk of spontaneous preterm delivery. Neither the method nor the gestational age of TOP has any effect on this lack of association.