How much is the risk for major birth defects increased in women with gestational diabetes mellitus (GDM)?

Updated: Apr 29, 2020
  • Author: Thomas R Moore, MD; Chief Editor: George T Griffing, MD  more...
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Among the general population, major birth defects occur in 1-2% of the population. In women with overt diabetes and suboptimal glycemic control before conception, the likelihood of a structural anomaly is increased 4- to 8-fold.

Although initial reports demonstrated anomaly rates as high as 18% in women with preexisting diabetes mellitus, [29] more recent studies, in patients who received more aggressive preconception and first trimester management, report anomaly rates between 5.1 and 9.8%. [30, 31]

Two-thirds of birth anomalies involve the cardiovascular and central nervous systems. Neural tube defects occur 13-20 times more frequently in diabetic pregnancies, and genitourinary, gastrointestinal, and skeletal anomalies are also more common.

It is notable that no increase in birth defects occurs among the offspring of fathers who have diabetes or the offspring of women who develop gestational diabetes after the first trimester. This suggests that periconceptional glycemic control is the main determinant of abnormal fetal development in diabetic women.

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