Major adverse pregnancy outcomes raise long-term mortality risks for mothers

Key takeaways:

• Any major adverse pregnancy outcome was tied to higher mortality risk for mothers that remained 30 to 46 years after delivery.
• Mortality risks were higher for women with multiple adverse pregnancy outcomes.

Women with preterm birth, small for gestational age infants, preeclampsia, hypertensive disorders or gestational diabetes had increased mortality risks persisting more than 40 years after delivery, researchers reported.

“To our knowledge, no studies have examined multiple adverse pregnancy outcomes across each woman’s reproductive life in relation to future mortality,” Casey Crump, MD, PhD, vice chair of research in the department of family and community medicine at McGovern Medical School and professor in the department of epidemiology at the School of Public Health at the University of Texas Health Sciences Center, and colleagues wrote. “Such studies could help elucidate the relative effects of specific adverse pregnancy outcomes on subsequent mortality, which may further improve clinical risk assessment and preventive interventions.”

Crump and colleagues conducted a national cohort study, published in JAMA Internal Medicine, using the Swedish Medical Birth Register to identify 2,195,667 women (median age at delivery, 27 years) with a singleton delivery and data on pregnancy duration and infant birth weight from 1973 to 2015. Researchers identified preterm birth, small for gestational age, preeclampsia, hypertensive disorders and gestational diabetes as major adverse pregnancy outcomes and identified deaths using the Swedish Death Register.

Primary outcome was all-cause and cause-specific mortality.

During 56 million person-years of follow-up, 4% of women died (median age at death, 59 years); 30% of women experienced at least one and 8% of women experienced at least two adverse pregnancy outcomes. The most common adverse outcomes were small for gestational age infants and preterm birth, which occurred in 10% and 5% of deliveries, respectively, and 14% and 8% of all women during reproductive years, respectively.

Gestational diabetes (adjusted HR = 1.52; 95% CI, 1.46-1.58), preterm birth (aHR = 1.41; 95% CI, 1.37-1.44), small for gestational age (aHR = 1.3; 95% CI, 1.28-1.32), hypertensive disorders (aHR = 1.27; 95% CI, 1.19-1.37) and preeclampsia (aHR = 1.13; 95% CI, 1.1-1.16) were all independently associated with all-cause mortality. These associations remained increased 30 to 46 years after delivery.

Overall, 14% of deaths were attributed to CVD, 49% to cancer, 4% to respiratory disorders, 1% to diabetes and 32% to other causes. All major adverse pregnancy outcomes were associated with a 1.5-fold to 2.5-fold higher CVD mortality risk. Women with preterm birth or small for gestational age infants had a more than double respiratory mortality risk and a 1.1-fold to 1.2-fold higher cancer mortality risk. Women with preterm birth or preeclampsia had a more than double diabetes mortality risk, and women with gestational diabetes had a 25-fold higher diabetes mortality risk.

At 30 to 46 years after delivery, mortality risks were higher for women with one (HR = 1.27; 95% CI, 1.24-1.3), two (HR = 1.56; 95% CI, 1.5-1.63) or at least three (HR = 1.84; 95% CI, 1.73-1.95) adverse pregnancy outcomes compared with women who never experienced an adverse pregnancy outcome.

“All five major adverse pregnancy outcomes should now be recognized as long-term risk factors for premature mortality,” the researchers wrote. “Women with adverse pregnancy outcomes need early preventive actions and long-term follow-up for timely detection and treatment of chronic disorders associated with early mortality.”