[Gestational diabetes mellitus and congenital malformations]

Maternal diabetes mellitus affects approximately 5% of all pregnancies. Pregestational diabetes mellitus has been associated with a high risk of spontaneous abortions and congenital malformations during the first trimester of pregnancy then is considered teratogenic. This frequency of birth defects is three to fivefold increased compared with general population. Although an association of gestational diabetes mellitus (GDM) with an increase of congenital malformations has not been demonstrated, some clinical and epidemiological studies of this possible association have reported the presence of GDM in mothers of children with congenital malformations.

Of this study was to compare the prevalence of congenital malformations associated with GDM in relation to pregestational diabetes mellitus and general population.

In the present study 3 groups were compared: the group I was integrated by 112 new born of mothers with GDM; in the group 2, there were 30 new born from women with gestational diabetes mellitus. 103 new born from healthy women integrated the group 3. All patients were recruited consecutively during a period of 18 months.

A total of 24 cases with congenital malformations were detected. The group with the higher prevalence was the group 2 (30%). We found a tendency to a higher risk of congenital malformations on the cases exposed to GDM (group 1) compared with the group not exposed (group 3). The analysis of the mothers background of the children from group 2 with congenital malformations showed a significant difference in the antecedent of previous macrosomic product in comparison with the antecedents of the mothers of the same group that bear healthy babies.

The results of the analysis in the studied population did not show an association between GDM and congenital malformations, although there is a tendency to a higher prevalence in comparison with not exposed population. This could be due to the heterogeneity of the GDM; an entity usually detected late in pregnancy, but probably present since the first weeks of gestation when the teratogenic effect could occur.

In the present study we found that the antecedent of previous macrosomic products is an important risk factor, therefore, such women require a close vigilance of the glucose levels before and during the first weeks of pregnancy in order to prevent congenital malformations, one of the principal causes of death in the new born.