Congenital Malformations

Many studies have noted congenital anomalies of infants born to women with gestational diabetes mellitus. The anomalies are similar to those found in women with Type I diabetes and include the cardiac, musculoskeletal, and central nervous systems . This suggests that gestational diabetes mellitus can cause anomalies during the organogenesis although this was not proved because testing of gestational diabetes mellitus does not occur until after 16 weeks of gestation.

The most frequent defect found in infants of GDM mothers were cardiac, followed by musculoskeletal and the nervous system. Minor anomalies and genetic syndromes have also been found to be of greater risk for infants from women with GDM. The greater the maternal glycemia, the greater risk of anomalies affecting more than one organ system although it is not possible to determine which systems may be at the most risk. Further the higher the glucose level the greater risk for multiple organ system anomalies.

Gestational diabetes combined with obesity creates the greatest risk for major and minor anomalies in infants. Obese women with gestational diabetes have a sevenfold greater risk of having an infant with craniofacial or musculoskeletal defect than non-obese, non-diabetic women.

The incidence of congenital anomalies occurs two to three times more frequently in pregestational diabetes pregnancies than in non-diabetic pregnancies however, there is question on whether the literature supports this rate of anomalies with GDM pregnancies. Some studies have only found limited congenital anomalies in infants of women with GDM. Moore, et al (18) found that women with GDM who were not obese had a greater risk of an infant with musculoskeletal defects but they did not find any greater risk of multiple anomalies. Other studies have disputed this claim. Bartha et al were not able to find any significant increase in congenital anomalies in GDM pregnancies.supports this argument indicating that GDM occurs in the second and third trimesters beyond the period of fetal morphologic development.