Pregnant young woman sitting on a bed preparing insulin dosage in insulin pen before injecting to represent gestational diabetes and other adverse pregnancy outcomes.
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Research led by Shanghai Jiao Tong University School of Medicine and the Chan School of Public Health in Boston suggests that there may be more long-term health risks associated with gestational diabetes than previously thought even in women who do not go on to develop type 2 diabetes.

Using data collected from more than 90,000 participants in the Nurses’ Health Study II, the investigators found that gestational diabetes was associated with a small but significant increase in mortality risk, particularly from cardiovascular causes, regardless of whether those of developed gestational diabetes went on to develop full blown type 2 diabetes.

However, the results showed that the increase in mortality was more pronounced in women with less healthy lifestyles suggesting that at least some of the risks could be addressed through lifestyle changes such as improved diet, reducing or stopping smoking and drinking alcohol, increasing exercise, losing weight and reducing cardiovascular risk factors such as high blood pressure and high cholesterol.

Gestational diabetes is increasingly more common and rates in the U.S., have increased from an average of 47.6 to 63.5 per 1000 live births between 2011 and 2019. As well as being at almost 10-fold increased risk of developing type 2 diabetes, women who experience gestational diabetes are thought to be at increased risk for cancer, chronic hypertension, and cardiovascular disease, but little research has looked into the impact on mortality.

This study, which is published in JAMA Internal Medicine, followed up participants of the Nurses’ Health Study II between 1989 and 2019. Those included were aged 25 to 42 years and reported at least one pregnancy of 6 months or more in duration when aged 18 years or older. Overall, 91,426 participants were included in this study aged 35 years on average and with an average body mass index of 24 at enrollment.

During the follow-up period (2,609,753 person-years), 3937 deaths occurred in the cohort, 255 from cardiovascular causes and 1397 from cancer. The results showed that women who had gestational diabetes during at least one pregnancy had a 28 percent higher mortality rate than those who did not. This association persisted after adjusting for potential confounding factors including later development of type 2 diabetes.

Certain factors raised mortality risk further among women who had a history of gestational diabetes including leading a less healthy lifestyle, having gestational diabetes in more than one pregnancy, development of hypertensive disorders in pregnancy and having a preterm birth or a baby of low birth weight.

When the researchers looked at deaths from cardiovascular disease or cancer, gestational diabetes increased the risk of cardiovascular mortality by 59 percent versus no gestational diabetes, but did not increase the risk of dying of cancer.

“Gestational diabetes may be etiologically linked to a greater risk of mortality, particularly cardiovascular disease (CVD) mortality, through shared mechanistic pathways that predate pregnancy, such as systemic inflammation… Meanwhile, the increased risk of CVD mortality may also be accelerated by reduced sex hormone–binding globulin levels, insulin resistance, and increased release of inflammatory cytokines implicated in the cause of gestational diabetes during pregnancy,” write the authors.

“Together, these data support the emerging concept that individuals who develop adverse pregnancy outcomes may have greater underlying susceptibility to chronic metabolic disorders before or during pregnancy that can be unveiled by increased physiological stress during pregnancy.”

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