Promoting healthy longevity should start young: pregnancy complications lift women’s risk of mortality in the next 50 years

In Singapore, about 15 to 20 per cent of pregnancies are complicated by gestational diabetes, 5 to 10 per cent of pregnancies are affected by hypertensive disorders of pregnancy, and more than 10 per cent of pregnancies end as pre-term delivery. Pregnancy is a critical reproductive event for women, with substantial life-long health implications.

This brings forward an important question: how would pregnancy complications inform women’s risk of mortality in the long-term? However, this is often understudied due to a lack of long-term follow-up data.

Homing in on this, Professor Cuilin Zhang, Director of the Global Centre for Asian Women’s Health (GloW) and a chaired professor in the Department of Obstetrics and Gynecology at the Yong Loo Lin School of Medicine, National University of Singapore (NUS Medicine), in collaboration with investigators from University of Pennsylvania and the National Institutes of Health (NIH), led a research team to investigate the question on how having pregnancy complications may inform one’s long-term mortality risk, relative to those without the complications.

They studied common pregnancy complications in association with total and cause-specific mortality more than 50 years after the complicated pregnancy. This study was recently published in Circulation.

The study followed up on more than 45,000 pregnant women in the United States (U.S), who were enrolled into a pregnancy study during their first pregnancy visit between the 1950s to the 1960s. Researchers recorded common pregnancy complications of preterm delivery, hypertensive disorder of pregnancy, and gestational diabetes/impaired glucose tolerance. They followed up with the participants after their index pregnancy.

Results showed that those who experienced any of these common pregnancy complications had an increased risk of mortality in the next 50 years after pregnancy. Particularly, pregnancies complicated by preterm delivery, hypertensive disorders of pregnancy, and gestational diabetes was associated with 7 per cent to 109 per cent, 9 per cent to 32 per cent, and a 14 per cent higher risk of all-cause mortality, respectively.

An interesting finding was that for women who had preterm deliveries, their risk and cause of mortality appeared to differ according to the reason for the preterm delivery. The risk of all-cause mortality, which refers to death by any cause, was highest in women who had a pre-labour cesarean delivery.

For cause-specific mortality, preterm deliveries due to spontaneous labour were associated with increased mortality from cardiovascular diseases. Preterm deliveries due to other reasons, such as premature rupture of the membrane and induced preterm were also associated with the increased mortality resulting from diabetes, kidney, and respiratory diseases.

These findings related to preterm deliveries highlight the importance of understanding the causes of preterm deliveries when assessing future risk of complications.

“Pregnancy is an early-life stress test for the mother’s underlying cardiometabolic health, as several major pregnancy complications are linked with an increased risk of high blood pressure, diabetes, and cardiovascular diseases, in studies conducted in the U.S and Europe. However, the roles of pregnancy complications on chronic diseases and long-term mortality in Asian women have not been well examined. Thus, studies among Asian women, with continued, long-term follow-ups are warranted to investigate the roles of pregnancy complications on their subsequent health status and to identify effective ways to improve the long-term health of women following complicated pregnancies” said Professor Zhang, senior author of the study.

“Our study provided compelling evidence to support the notion that promoting healthy longevity should start young and early—a concept that has been increasingly promoted by the research community at the NUS Medicine”, added Professor Zhang.