The association between high-normal blood pressure and the development of preeclampsia in twin pregnancies

Objective: We sought to determine if women with twin pregnancies and blood pressure (BP) above the 95th percentile but within normal ranges (i.e. less than 140 systolic and 90 diastolic) are at increased risk of hypertensive disorders of pregnancy.Methods: Retrospective cohort study of all women with twin pregnancies being cared for by a single Maternal Fetal Medicine practice between 2012 and 2018. We identified all women who had a systolic blood pressure (SBP) or diastolic blood pressure (DBP) above the 95th percentile but less than 140 systolic and 90 diastolic at any point during pregnancy. Based on prior publications, the 95th percentile was defined as: a SBP 121-139 mmHg up to 30 weeks or 131-139 mmHg after 30 weeks, a DBP 81-89 mmHg up to 34 weeks or 85-89 mmHg after 34 weeks. We excluded women diagnosed with chronic hypertension either before or during pregnancy. The primary outcome was the development of preeclampsia. Chi-square and logistic regression were used.Results: A total of 457 patients met the inclusion criteria, of whom 109 (23.9%) had either a systolic or diastolic BP above the 95th percentile (but normal) at any time during pregnancy. These women were significantly more likely to develop preeclampsia (30.3 versus 12.6%, p < .001, aOR 2.32 (1.31, 4.09)) and gestational hypertension without preeclampsia (16.5 versus 4.6%, p < .001, aOR 4.27 (2.01, 9.07)).Conclusions: In women with twin pregnancies, a high-normal systolic or diastolic BP (above 120 systolic or 80 diastolic prior to 30 weeks, or above 130 systolic or 84 diastolic after 30 weeks) is associated with a significantly increased risk of gestational hypertension and preeclampsia.