Major studies suggest that pregnancy increases cardiovascular risk across all maternal ages and that older patients face more events due to higher baseline risk, rather than primarily through age-related pregnancy-specific mechanisms.
Study: Maternal age and pregnancy-related cardiovascular complications. Image credit: Agatha Jennifer / Shutterstock
Older maternal age does not by itself exacerbate pregnancy-specific cardiovascular complications during pregnancy. Rather, pregnancy appears to uniformly amplify women’s baseline cardiovascular risk, as reported in a new study published in the journal Physiology. nature communications.
Background of maternal age and cardiovascular risk
Pregnancy-related cardiovascular complications are major risk factors for maternal mortality. Approximately 20-30% of maternal deaths worldwide occur due to these complications. In the general population, the risk of cardiovascular events increases with increasing age. Some studies also suggest that women who become pregnant after age 35 are at increased risk for adverse pregnancy outcomes. However, it remains unclear whether maternal age increases pregnancy-specific risk of pregnancy-related cardiovascular complications.
Most previous studies have focused on pregnancy-specific risks without distinguishing them from maternal baseline cardiovascular risk. Therefore, it remains unclear whether aging specifically increases pregnancy-specific cardiovascular risk or whether older women simply have a higher baseline cardiovascular risk.
To address this gap in the literature, Weill Cornell Medicine researchers analyzed publicly available anonymized claims data for delivery-related hospitalizations across 11 U.S. states between 2016 and 2021.
They compared each patient’s risk of developing a major adverse cardiovascular event during a defined pregnancy/postpartum risk window to the risk of such an event occurring during an equivalent non-pregnant control period.
Findings of cardiovascular events during pregnancy
Researchers identified 2,710,983 patients with a first recorded pregnancy, of whom 12,059 experienced a major adverse cardiovascular event during pregnancy or the puerperium, compared with 1,685 in a comparable control period one year later.
The most commonly experienced adverse cardiovascular events were venous thromboembolism, cardiomyopathy, and heart failure. Of the patients who had a major adverse cardiovascular event, 240 died, representing almost 50% of all maternal deaths in the study population. Among survivors, nearly 10% required care in a rehabilitation facility, nursing home, or home health care.
Overall, the gestational and postpartum periods were associated with a 7-fold higher risk of major adverse cardiovascular events compared with the control period. However, this risk induction compared to patients’ baseline cardiovascular risk did not vary by maternal age.
However, the absolute risk of induction remained stable at approximately 3 excess cardiovascular events per 1,000 pregnancies until age 31 years, but steadily increased thereafter, reaching 10 excess events per 1,000 pregnancies by age 44 years. These findings indicate that cardiovascular events occur more frequently during pregnancy in older patients, primarily because of higher baseline cardiovascular risk and not because older age enhances pregnancy-specific cardiovascular mechanisms.
The observed association between maternal age and cardiovascular risk was similar across subgroups defined by race and ethnicity, insurance type, household income, region, and comorbidities.
Impact on baseline cardiovascular health
This study reveals that maternal age does not significantly influence the relative increase in pregnancy-related adverse cardiovascular events during pregnancy. Rather, pregnancy appears to amplify patients’ non-pregnant baseline cardiovascular risk.
In other words, this study suggests that baseline cardiovascular health may be more important than age alone. This means that healthy older women with low baseline cardiovascular risk do not necessarily have a higher pregnancy-specific relative risk than younger women with higher cardiovascular risk factors.
Remarkably, the researchers found that patients with one or more comorbidities (most commonly hypertension and asthma) had an excess risk induction of as many as 20 cardiovascular events per 1,000 pregnancies by age 45. This finding calls for further investigation into why asthma is overrepresented among patients with pregnancy-related cardiovascular complications.
In the study population, black women were shown to have a higher risk of experiencing cardiovascular events than white women. However, in race-stratified analyses, the increased relative risk associated with pregnancy did not vary by maternal age. This suggests that other factors, such as social determinants of health and access to risk factor management, may explain the racial disparities observed here.
Overall, this study suggests that addressing and managing a woman’s cardiovascular health before pregnancy can reduce the risk of pregnancy-related maternal cardiovascular complications. Rather than simply assuming that younger age is a protective factor against pregnancy-related cardiovascular complications, obstetricians and gynecologists should consider baseline assessment of cardiovascular risk, screening, close follow-up, and optimization of modifiable risk factors in women planning pregnancy.
Study limitations and generalizability
This study used hospital discharge diagnosis codes to identify serious adverse cardiovascular events that may have resulted in misclassification. Additionally, the study lacked information about drugs, particularly aspirin, which is commonly used to prevent preeclampsia in high-risk patients during pregnancy. These drugs may have cardiovascular risk modulating effects.
This study included patients from different states in the United States, which may limit the generalizability of the observed associations to global populations. However, because the study population represents 25% of the U.S. population, these results can be generalized to other countries and health systems with broadly similar characteristics.
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