Women who experience miscarriage are more likely to develop gestational diabetes, reports a study just published in JAMA Network Open, the weekly international, peer-reviewed, open access medical journal published by the American Medical Association. (Gestational diabetes is characterized by high blood sugar during pregnancy and normally goes away after delivery, but women with the condition are at increased risk of developing type 2 diabetes.)
According to the authors, who are based at Shanghai Key Laboratory of Maternal Fetal Medicine, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, China, “Gestational diabetes (GD) is one of the most common and important complications of pregnancy. Identifying pregnant women who are at high risk of GD is crucial for implementing early prevention and intervention.” They also said that nearly one out of three pregnancies (30%) end in miscarriage.
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The researchers derived their data from the records of 102,259 pregnant women who had received routine care at a hospital in Shanghai between 2014 and 2019. The average age of the women was 29.8. The women’s history of miscarriage and intentional abortion were taken from their medical records. The researchers excluded women who had previously had multiple pregnancies, gestational diabetes, and certain complicating factors, such as kidney trouble, high blood pressure, regular diabetes, and thyroid issues. They also separated those who had intentional, or induced, abortions from those who had spontaneous abortions, or SABs, more commonly known as miscarriage. Gestational diabetes was diagnosed with an oral glucose tolerance test. About 14% of the women had earlier had a miscarriage, 17.5% had undergone an intentional, or induced, abortion, and 3.9% had experienced both.
Miscarriage linked to higher risk of gestational diabetes in later pregnancy
The researchers determined that the women who had previously had a miscarriage, or SAB, had a 25% higher risk of experiencing gestational diabetes during a later pregnancy. They also found that the number of miscarriages was a factor — the greater the number of miscarriages, the greater the risk of gestational diabetes. Compared to pregnant women with no history of abortion, the relative risk for gestational diabetes rose by 18% for pregnant women with one miscarriage. For women with two miscarriages, the risk rose by 41%, and for women with more than two miscarriages, the risk rose by 43%. Interestingly, the data showed no association between a history of induced abortion and gestational diabetes.
The researchers pointed out that their study was not the first to report a link between miscarriage and gestational diabetes. In a large study of gestational diabetes among Chinese women published in 2009, researchers reported miscarriage to be a risk factor, along with advanced maternal age, pre-pregnancy overweight or obesity, and a family history of diabetes.
Until further research is done, the authors of the study could only speculate on the reasons for the link between miscarriage and gestational diabetes. They suggested that it might have to do with inflammation and with oxidative stress (a condition that develops when there is an excess of free radicals in the body’s cells). These two factors are known to raise the risks of both cardiovascular diseases and metabolic diseases such as diabetes. In conclusion, they wrote, “Our findings 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 (e.g., eating more healthfully and doing regular physical activity). Considering the short- and long-term adverse effects of GD on both mothers and their offspring, our findings may also have potential public health implications.”