Preconception Blood Pressure and Its Change Into Early Pregnancy: Early Risk Factors for Preeclampsia and Gestational Hypertension

Abstract

Preeclampsia and gestational hypertension are common complications of pregnancy associated with significant maternal and infant morbidity. Despite extensive research evaluating risk factors during pregnancy, most women who develop a hypertensive disorder of pregnancy are not considered high-risk and strategies for prevention remain elusive. We evaluated preconception blood pressure and its change into early pregnancy as novel risk markers for development of a hypertensive disorder of pregnancy. The EAGeR (Effects of Aspirin in Gestation and Reproduction) trial (2007-2011) randomized 1228 healthy women with a history of pregnancy loss to preconception-initiated low-dose aspirin versus placebo and followed participants for up to 6 menstrual cycles attempting pregnancy and throughout pregnancy if they became pregnant. Blood pressure was measured during preconception and throughout early gestation. The primary outcomes, preterm preeclampsia, term preeclampsia, and gestational hypertension, were abstracted from medical records. Among 586 women with a pregnancy >20 weeks' gestation, preconception blood pressure levels were higher for preterm preeclampsia (87.3±6.7 mm Hg mean arterial pressure), term preeclampsia (88.3±9.8 mm Hg), and gestational hypertension (87.9±9.1 mm Hg) as compared with no hypertensive disorder of pregnancy (83.9±8.6 mm Hg). Change in blood pressure from preconception into very early pregnancy was associated with development of preeclampsia (relative risk, 1.13 [95% CI, 1.02-1.25] per 2 mm Hg increase in mean arterial pressure at 4 weeks' gestation), particularly preterm preeclampsia (relative risk, 1.21 [95% CI, 1.01-1.45]). Randomization to aspirin did not alter blood pressure trajectory or risk of hypertension in pregnancy. Preconception blood pressure and longitudinal changes during early pregnancy are underexplored but crucial windows in the detection and prevention of hypertensive disorders of pregnancy. Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00467363.

Keywords: blood pressure; hypertension; preeclampsia; pregnancy; risk factors.

Figure 1.

Trajectory of mean (standard error) systolic (A) and diastolic (B) blood pressure from preconception through 20 weeks’ gestation by development of hypertension in pregnancy.

Figure 2.

Effect modification by treatment assignment (A), parity (B) and body mass index (C) of the risk of hypertension in pregnancy by preconception blood pressure (per 2 mmHg) and change in blood pressure (per 2 mmHg increase) from preconception to gestational weeks 4, 8, 12, 16 and 20. *p-interaction <0.05