Effects of lactation on postpartum blood pressure among women with gestational hypertension and preeclampsia

Background Women with a history of hypertensive disorders of pregnancy are at an increased risk of hypertension and cardiovascular disease in later life. Lactation has been associated with a reduced risk of maternal hypertension, both in the postpartum period and later life. However, little is known about whether lactation is also cardioprotective in women with hypertensive disorders of pregnancy such as preeclampsia or gestational hypertension. Objective This study aimed to characterize the relationship between lactation and postpartum blood pressure among women with preeclampsia and gestational hypertension. Study Design Data were obtained from women who participated in the Prenatal Exposures and Preeclampsia Prevention study (n = 379; 66% African American; 85% overweight or obese). Women enrolled during pregnancy and attended a postpartum visit (on average, 9.1 months after delivery) during which data on lactation duration and blood pressure were collected. The significance of the associations between postpartum blood pressure and lactation among women who remained normotensive during pregnancy, developed gestational hypertension, or developed preeclampsia were assessed with an analysis of variance. Linear regression models were used to adjust for maternal age, race, education, prepregnancy weight, and time since delivery. Results Gestational hypertension affected 42 subjects (11%) and preeclampsia affected 33 (9%). Lactation was reported by 217 (57%) with 78 (21%) reporting ≥ 6 months of lactation. Women who lactated were somewhat older, more educated, and had higher socioeconomic status. Among women who had gestational hypertension, lactation was associated with lower systolic blood pressure (P = .02) and diastolic blood pressure (P = .02). This association persisted after adjustment for age, race, education, prepregnancy weight, and time since delivery. However, for women who had preeclampsia and women who remained normotensive during pregnancy, lactation was not associated with postpartum blood pressure in either bivariate or multivariate analyses. Conclusion This study found that lactation is associated with lower postpartum blood pressure among overweight women who develop gestational hypertension but not among women who develop preeclampsia. Future studies are needed to explore the association of lactation and blood pressure in later life for women with hypertensive disorders of pregnancy.