Objective: To investigate if there is an increased risk for recurrence of hypertensive disorder in pregnancy with a new partner and whether this is affected by maternal age and the interbirth interval through use of familial material.
Methods: Data on 614 multiparous women, with confirmed de novo hypertensive disorder in a first pregnancy, were used to assess the effect of paternity and interbirth interval on recurrence of hypertensive disorders.
Results: There were 121 women (19.7%) who had changed partner. Recurrent hypertension occurred in 318 women (64.5%) with the same partner and in 75 women (62%) with a new partner. The odds ratio (OR) for recurrence with the same partner was 1.115 (95% CI 0.739-1.680) and with a new partner 0.897 (95% CI 0.595-1.353). The mean interbirth interval was longer for women with recurrent hypertension (4.9 vs. 4.0 years, p = 0.0002). The OR for developing recurrent hypertensive disorder was 1.154 (95% CI 1.049-1.269) for every interval year with the same partner and 1.145 (95% CI 0.958-1.368) with a new partner after correction for maternal age.
Conclusion: In women with a positive family history and previous hypertension in pregnancy, change of paternity does not influence the risk of recurrence. Increasing interbirth interval may account for a 15% recurrence risk for each year, independent of maternal age. There was no indication that a change of partner conferred any influence on the recurrence risk that is not explained with birth interval or age.