Maternal risk of hypertension 7-15 years after pregnancy: clues from the placenta.

Objective: To assess whether pre-eclampsia (PE)-related placental/extraplacental membrane findings are linked to moderately elevated blood pressure (BP) in pregnancy and later-life hypertension.

Design: Prospective cohort.

Setting: 52 prenatal clinics, 5 Michigan communities.

Sample: The POUCH Study recruited women at 16-27 weeks' gestation (1998-2004) and studied a sub-cohort in depth. This sample (n = 490) includes sub-cohort women with detailed placental assessments and cardiovascular health evaluations 7-15 years later in the POUCHmoms follow-up study.

Methods: PE-related placental/extraplacental membrane findings (i.e. mural hyperplasia, unaltered/abnormal vessels or atherosis in decidua; infarcts) were evaluated in relation to pregnancy BP and odds of Stage 2 hypertension at follow up using weighted polytomous regression. Follow-up hypertension odds also were compared in three pregnancy BP groups: normotensives (referent) and moderately elevated BP with or without PE-related placental/extraplacental membrane findings.

Main Outcome Measures: Stage 2 hypertension (SBP ≥140 mmHg and/or DBP ≥90 mmHg, or using antihypertensive medications) at follow up.

Results: After excluding women with pregnancy hypertension (i.e. chronic, PE, gestational), mural hyperplasia and unaltered/abnormal decidual vessels were each associated with Stage 2 hypertension at follow up: adjusted odds ratio (aOR) = 2.7, 95% CI 1.1-6.6, and aOR = 1.7 (95% CI 0.8-3.4), respectively. Women with moderately elevated BP in pregnancy and evidence of mural hyperplasia or unaltered/abnormal decidual vessels had greater odds of Stage 2 hypertension at follow up: aOR = 4.5 (95% CI 1.6-12.5 and aOR = 2.6, 95% CI 1.1-5.9, respectively.

Conclusions: PE-related placental/extraplacental membrane findings help risk-stratify women with moderately elevated BP in pregnancy for later development of hypertension.

Tweetable Abstract: Placental findings associated with mother's risk of later-life hypertension.