Women who have experienced hypertensive disorders of pregnancy (HDP) face a doubled risk of cardiovascular disease compared with those who have had normotensive pregnancies – and their risk factor levels remain higher through age 50 and beyond. Hypertensive disorders of pregnancy and cardiovascular disease share a host of common modifiable risk factors including adiposity, hypertension, hyperglycemia, and dyslipidemia. Although it is not known how much of the excess pregnancy-related CVD risk is associated with these elevated risk factors, they may be an important target for prevention in women with a history of HDP.
While previous studies have quantified the increased risk women for with HDP, prior research aims to estimate the proportion of conventional cardiovascular risk factors associated with elevated CVD risk. A 2019 prospective cohort study of pregnant women found that 77% of excess cardiovascular risk for women with a history of hypertensive disorders of pregnancy is attributed to elevated blood pressure and BMI levels.
Association of Conventional Cardiovascular Risk Factors with CVD After HDP
Led by Dr. Eirin Beate Haug from the Norwegian University of Science and Technology, a team of researchers conducted a population-based cohort study using data from the HUNT study. In order to quantify the excess risk of CVD in women with a history of HDP, study authors used mediation analysis to examine BMI, blood pressure, glucose levels, and lipid levels in 23,885 women.
For the purposes of the study, women identified with HDP were those who had ever experienced preeclampsia or gestational hypertension below the age of 40. Out of the cohort, 9% of women (2,119 participants) had a history of HDP – 1,391 experienced preeclampsia at least once, and 728 experienced gestational hypertension.
Investigators found that 1,688 participants had experienced at least 1 cardiovascular event, and 92.7% of those had a validated CV event during the median follow-up period of 18 years. Of these, 552 had a myocardial infarction, 233 experienced heart failure, and 878 had a cerebrovascular event. After adjusting hazard ratios for age, maternal birth year, education level, smoking, and family medical history, researchers confirmed the heightened CVD risk for women with a history of HDP.
Participants between the ages of 40 and 70 with a history of HDP had a significantly higher risk of any cardiovascular event than women without any history of HDP, as did women with previous preeclampsia and previous gestational hypertension. In women over the age of 70, the relationship was reversed as those with a history of HDP experienced a lower CV event risk than women with normotensive pregnancies, however, this was not statistically significant and may have been the result of survivor bias.
Conventional Cardiovascular Risk Factors Identified
“Blood pressure plays a substantial role in driving the excess cardiovascular risk in women who experienced preeclampsia and an even larger role in women who experienced gestational hypertension,” lead author Dr. Haug commented.
Researchers found that for participants between the ages of 40 and 70, 41% of the association between HDP and CVD was connected to BMI levels while 60% was tied to systolic blood pressure and 73% to diastolic blood pressure. Analyzing both BMI and BP, investigators found that BMI and systolic BP were linked to 67% of the HDP and CVD association while BMI and diastolic BP were associated with 79%. Overall, blood pressure and body mass index were tied to 77% of the excess risk of CVD in women with a history of HDP; glucose and lipid levels were associated with lesser proportions.
Identifying and quantifying the proportion of conventional cardiovascular risk factors involved in elevated CVD risk in women with a history of HDP may help further prevention efforts and improve early detection of potential comorbidities. These findings help to illustrate the importance of decreasing the levels of blood pressure and body mass index in pregnant women to reduce overall cardiovascular risk and improve long-term health outcomes.