Partner change and perinatal outcomes: a systematic review.

Epidemiological studies suggest that partner change may affect perinatal outcomes in subsequent pregnancies. We conducted a systematic review on the association between paternity change and perinatal outcomes. We searched the literature in MEDLINE using keywords 'paternity', 'partner', 'pre-eclampsia', 'preterm birth', 'low birth weight', and 'birth defects' from 1966 to 2005. We identified 19 studies that examined the association between partner change and specific perinatal outcomes: 12 on pre-eclampsia or hypertension in pregnancy, three on birth defects, three on preterm birth, and two on low birthweight. Partner change was consistently associated with an increased risk of pre-eclampsia or hypertension in pregnancy in 11 of 12 studies (the unadjusted relative risk [RR] ranging from 1.2 to 8.3). However, after controlling for birth interval as a confounder in multivariate analysis, two studies using the same birth registry data showed a modestly reduced risk in relation to partner change (RR=0.84 and 0.73, respectively), while two studies found a slightly increased risk (both RR=1.3). Retrospective cohort studies presented inconsistent findings on the association between partner change and risk of preterm birth and low birthweight. Finally, three population-based cohort studies demonstrated that partner change significantly reduced the recurrence of the same or similar birth defects in subsequent births (RRs ranging from 0.1 to 0.76). We conclude that partner change reduces the risk of recurrent same birth defects. However, epidemiological evidence on the effect of partner change on pre-eclampsia, preterm birth and low birthweight is inconclusive. Whether birth interval should be controlled for in the association between partner change and pre-eclampsia warrants caution.