Key Point:  In Black patients, history of pregnancy complications is associated with increased risk for cardiometabolic disease and early mortality.

Pregnancy complications are associated with higher mortality risk and are more prevalent in Black individuals, according to the results published in Pregnancy Complications and Long-Term Mortality.

Researchers conducted a prospective cohort study that included 48,197 pregnant individuals from 12 clinical centers in the United States from 1959 to 1966. Pregnancy complications were classified as preterm delivery (PTD), hypertensive disorders, and gestational diabetes/impaired glucose tolerance (GDM/IGT). PTDs were classified into subtypes: preterm spontaneous labor, premature rupture of the membranes (PROM), preterm induced labor, preterm prelabor cesarean, and preterm unknown reason. Hypertensive disorders were classified into chronic hypertension, gestational hypertension, preeclampsia/eclampsia, and superimposed preeclampsia or eclampsia. Patients were followed from the year of the index pregnancy through 2016 or death. The National Death Index was used to define all-cause mortality and to identify causes of death. 

Adjusted hazard ratios (aHRs) for all-cause mortality and cause-specific mortality were calculated for each pregnancy complication via Cox proportional hazard regressions. Of the participants enrolled, 9 patients died during the index pregnancy and were excluded. The final population included 46,551 participants (45% Black; 46% White). The median follow-up time was 52 years (IQR, 45-54). As of 2016, mortality for Black participants was 41% compared with 37% for White participants. Cardiovascular disease and cancer were the top 2 leading causes of death. 

In the final analysis, 15% of the total pregnancies were preterm. All preterm deliveries were associated with an increased prevalence of all-cause mortality. The aHRs for preterm spontaneous labor were 1.07 (95% CI, 1.03-1.12), 1.23 (1.05-1.44) for preterm PROM, 1.31 (95% CI, 1.03-1.66) for preterm induced labor, 2.09 (95% CI, 1.75–2.48) for preterm prelabor cesarean delivery, and 0.92 (95% CI, 0.79–1.07) for preterm unknown reason. Black patients experienced a more significant proportion of spontaneous preterm deliveries (18%) compared with White patients (7%; P =.009); no significant differences were observed in the HRs for the other preterm subtypes.

Higher incidence of some complications in Black individuals and differential associations with mortality risk suggest that disparities in pregnancy health may have life-long implications for earlier mortality.

The overall incidence of hypertension was 4%, 2%, 1%, and 2% for chronic hypertension, gestational hypertension, preeclampsia/eclampsia, and superimposed preeclampsia/eclampsia, respectively. All hypertensive disorders, except chronic hypertension, were associated with an overall increase in all-cause mortality. The HR for gestational hypertension was 1.09 (95% CI, 0.97-1.22), 1.14 (95% CI, 0.99-1.32) for preeclampsia/eclampsia, and 1.32 (95% CI, 1.20-1.46) for superimposed preeclampsia/eclampsia. The researchers found that Black patients had a higher likelihood of chronic hypertension (6% versus 3%) and superimposed preeclampsia/eclampsia (3% versus 1%) compared with White patients (P =.05). 

Overall, 1% of the study population experienced GDM/IGT. No significant differences in incidence or risk of all-cause mortality due to GDM/IGT between Black and White patients were observed by the authors (P=.92). However, any individuals with GDM/IGT had a higher risk of all-cause mortality (aHR, 1.14; 95% CI, 1.00-1.30).

A significant limitation of this study is its time frame. In the 1950s to 1960s, the prevalence of pregnancy complications was skewed based on changing cultures and increased risk factors that may decrease relevancy to modern practice. 

Reference

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