The paternal role in pre-eclampsia and giving birth to a small for gestational age infant; a population-based cohort study

Objective: To estimate the effect of partner change on risks of pre-eclampsia and giving birth to a small for gestational age infant. Design: Prospective population study. Setting: Sweden. Participants: Women with their first and second successive singleton births in Sweden between 1990 and 2006 without pregestational diabetes and/or hypertension (n=446 459). Outcome measures: Preterm (<37 weeks) and term (>= 37 weeks) pre-eclampsia, and giving birth to a small for gestational age (SGA) infant. Risks were adjusted for interpregnancy interval, maternal age, body mass index, height and smoking habits in second pregnancy, years of involuntary childlessness before second pregnancy, mother's country of birth, years of formal education and year of birth. Further, when we calculated risks of SGA we restricted the study population to women with non-pre-eclamptic pregnancies. Results: In women who had a preterm pre-eclampsia in first pregnancy, partner change was associated with a strong protective effect for preterm pre-eclampsia recurrence (OR 0.24; 95% CI 0.07 to 0.88). Similarly, partner change was also associated with a protective effect of recurrence of SGA birth (OR 0.75; 95% CI 0.67 to 0.84). In contrast, among women without SGA in first birth, partner change was associated with an increased risk of SGA in second pregnancy. Risks of term pre-eclampsia were not affected by partner change. Conclusions: There is a paternal effect on risks of preterm pre-eclampsia and giving birth to an SGA infant.