Heterogeneity in the risk of cardiovascular disease mortality after the hypertensive disorders of pregnancy across mothers' lifetime reproductive history

Abstract

BackgroundPrior studies on maternal cardiovascular disease (CVD) mortality and hypertensive disorders of pregnancy (HDP) have focused only on a woman's first birth and have not accounted for successive affected pregnancies.ObjectivesThe objective of this study is to identify mothers' risk of CVD mortality considering lifetime reproductive history.MethodsWe used data from the Medical Birth Registry of Norway, the Norwegian Cause of Death Registry, and the Norwegian National Population Register to identify all mothers who gave birth from 1967 to 2020. Our outcome was mothers' CVD death before age 70. The primary exposure was the lifetime history of HDP. The secondary exposure was the order of HDP and gestational age at delivery of pregnancies with HDP. We used Cox regression models to estimate hazard ratio (HR) and 95% confidence interval (CI), adjusting for education, mother's age, and year of last birth. These models were stratified by the lifetime number of births.ResultsAmong 987,378 mothers, 86,294 had HDP in at least one birth. The highest CVD mortality, relative to mothers without HDP, was among those with a pre‐term HDP in their first two births, although this represented 1.0% of mothers with HDP (HR 5.12, 95% CI 2.66, 9.86). Multiparous mothers with term HDP in their first birth only had no increased risk of CVD relative to mothers without HDP (36.9% of all mothers with HDP; HR 1.12, 95% CI 0.95, 1.32). All other mothers with HDP had a 1.5‐ to 4‐fold increased risk of CVD mortality.ConclusionsThis study identified heterogeneity in the risk of CVD mortality among mothers with a history of HDP. A third of these mothers are not at higher risk compared to women without HDP, while some less common patterns of HDP history are associated with severe risk of CVD mortality.

Harnessing women's full reproductive history in assessing cardiovascular risk

“…In addition to one-child mothers, the risk should be evaluated in other subgroups of women. In this special issue, Wyatt and colleagues 7 highlight the heterogeneity in the risk of CVD associated with HDP based on parity and order of HDP occurrence.…”

“…For example, women who experience HDP in their first pregnancy and remain normotensive in subsequent pregnancies may have a different CVD risk profile than women with other patterns of complications and might be less in need of follow-up for CVD prevention. 1,7 Johnston et al highlight the limitations of using administrative data when evaluating the link between HDP and CVD, with reimbursement systems possibly playing a role in coding. Birth registries, such as those in Nordic countries are ideal data sources for surveillance purposes, as a result of their longitudinal capture of births and availability of historical data on a woman's reproductive history.…”