Pregnant women with a history of spontaneous abortion had a significantly increased risk of gestational diabetes in subsequent pregnancies, based on data from more than 100,000 women.
Gestational diabetes is associated not only with adverse perinatal outcomes, but also with an increased risk of long-term cardiovascular and metabolic health issues in mothers and children, wrote Yan Zhao, PhD, of Tongji University, Shanghai, and colleagues.
Previous studies also have shown that spontaneous abortion (SAB) is associated with later maternal risk of cardiovascular disease and venous thromboembolism, the researchers said. The same mechanisms might contribute to the development of gestational diabetes, but the association between abortion history and gestational diabetes risk in subsequent pregnancies remains unclear, they added.
In a study published in JAMA Network Open, the researchers identified 102,259 pregnant women seen for routine prenatal care at a single hospital in Shanghai between January 2014 and December 2019. The mean age of the women was 29.8 years.
During the study period, 14,579 women experienced SAB (14.3%), 17,935 experienced induced abortion (17.5%), and 4,017 experienced both (11.9%).
In all, 12,153 cases of gestational diabetes were identified, for a prevalence of 11.9%. The relative risk of gestational diabetes was 1.25 for women who experienced SAB and 1.15 for those who experienced both SAB and induced abortion, and the association between SAB and gestational diabetes increased in a number-dependent manner, the researchers said. The increase in relative risk for gestational diabetes in pregnant women with one SAB, two SABs, and three or more SABs was 18%, 41%, and 43%, compared to pregnant women with no SAB history.
However, no association appeared between a history of induced abortion and gestational diabetes, the researchers said. “To date, no study has reported the association of prior induced abortion with gestational diabetes,” they wrote.
The study findings were limited by several factors including the reliance on self-reports for history of SAB and therefore possible underreporting, the researchers noted. Other limitations included the lack of data on the timing of SABs; therefore, the time between SAB and gestational diabetes diagnosis could not be included in the analysis, they said. Unknown variables and the inclusion only of women from a single city in China might limit the generalizability of the results, they added.
More research is needed to understand the biological mechanisms behind the association between SAB and gestational diabetes, an association that has potential public health implications, they noted. However, the results suggest that “pregnant women with a history of SAB, especially those with a history of recurrent SAB, should attend more antenatal visits to monitor their blood glucose and implement early prevention and intervention,” such as healthful eating and regular exercise, they wrote.
Findings confirm, not surprise
The diagnosis of gestational diabetes in the current study “was made with a slightly different test than we typically use in the United States – a 1-hour nonfasting glucola followed by a confirmatory 3-hour fasting glucola,” Sarah W. Prager, MD, of the University of Washington, Seattle, said in an interview. The current study of both SAB and gestational diabetes is important because both conditions are very common and have been the focus of increased attention in the popular media and in scientific study, she said.
Dr. Prager said she was not surprised by the findings of a link between a history of gestational diabetes and a history of SAB, “but the association is likely that people at risk for gestational diabetes or who have undiagnosed diabetes/glucose intolerance are more likely to experience SAB,” she noted. “I would be surprised if the direction of the association is that SAB puts people at risk for gestational diabetes; more likely undiagnosed diabetes is a risk factor for SAB,” she added. “Perhaps we should be screening for glucose intolerance and other metabolic disorders more frequently in people who have especially recurrent SAB, as the more miscarriages someone had, the more likely they were in this study to be diagnosed with gestational diabetes;” or perhaps those with a history of SAB/recurrent SAB should be screened closer to 24 weeks’ than 28 weeks’ gestation to enable earlier intervention in those more likely to have gestational diabetes, Dr. Prager said.
The study was supported by the Key Program of the National Natural Science Foundation of China, the National Natural Science Foundation of China, the National Key Research and Development Program of China, the Shanghai Municipal Medical and Health Discipline Construction Projects, and the Shanghai Rising-Star Program. The researchers and Dr. Prager had no financial conflicts to disclose. Dr. Prager serves on the editorial advisory board of Ob.Gyn. News.