Association between hypertensive disorders of pregnancy and the risk of postpartum hypertension: a cohort study in women with gestational diabetes.

Previous studies in general people indicated that hypertensive disorders of pregnancy (HDP) increased the risk of subsequent hypertension after delivery. Some studies found that women with gestational diabetes mellitus (GDM) had an increased risk of HDP. However, very few studies have assessed the association between HDP and the risk of postpartum hypertension among GDM women. To evaluate the association between HDP and the risk of postpartum hypertension among GDM women, a retrospective cohort study was conducted in 1261 women with prior GDM at their postpartum 1-5 years using the baseline data from Tianjin Gestational Diabetes Mellitus Prevention Program. Cox regression models were applied to assess the single and joint associations of having a history of HDP, maternal pre-pregnancy Body mass index (BMI) (normal weight, overweight and obesity), and weight change from preconception to post-delivery with the risk of subsequent hypertension among the GDM women. We found that GDM women with a history of HDP, high pre-pregnancy BMI and weight gain >7 kg from preconception to post-delivery had an increased risk of postpartum hypertension. Joint effects analysis revealed that the positive association between a history of HDP in the index pregnancy and the risk of postpartum hypertension was consistent in GDM women with different levels of pre-pregnancy BMI or weight gain from preconception to post-delivery. In conclusion, a history of HDP, high pre-pregnancy BMI and weight gain >7 kg from preconception to post-delivery increase the risk of subsequent hypertension in postpartum 1-5 years among GDM women.