Obesity in mothers is one of the most decisive factors contributing to the appearance of congenital malformations in their children

Jul 16 2004

A study of more than 2000 children of women with gestational diabetes (the diabetes that some women get during pregnancy) has revealed that obesity in mothers is one of the most decisive factors contributing to the appearance of congenital malformations in their children, even more so than the seriousness of the diabetes.

The research, published in the european journal Diabetologia, has been carried out by a research team from the Universitat Autònoma de Barcelona and Hospital de Sant Pau in Barcelona.

It has been known since the 1960s that children of women with diabetes before pregnancy have a higher possibility of having congenital malformations, which are primarily related with the mother’s degree of hyperglycemia (high blood sugar) during the period in which the embryo’s organs are forming. In the children of women with gestational diabetes, which is first detected during pregnancy, the risk of malformations does not increase so much, but it still exists. In this case, during the period when the embryo’s organs are forming the glucose levels are usually fairly unaltered.

A research team from the Universitat Autònoma de Barcelona and the Hospital de Sant Pau headed by Doctor Rosa Corcoy have come to an unexpected conclusion after analysing the relationship between the mother’s glucose levels and congenital malformations in the children of mothers with gestational diabetes. Surprisingly, the body mass index, which indicates obesity, is more important for predicting malformations than other variables that indicate the seriousness of the maternal diabetes mellitus.

In a study of 2060 children, the researches decided to include the body mass index as a variable for the statistical analysis now that it has been demonstrated that obesity plays a part in congenital malformations in embryos, especially those related to the heart and the central nervous system. According to the study’s results, the mother’s degree of obesity is the main predicting factor for cardiac malformations and minor malformations, and the only factor able to predict renal and urinary tract malformations. The seriousness of the mother’s gestational diabetes, however, was the only factor that could predict skeletal malformations.

Previous studies have not identified the degree of obesity as contributing to the risk of cardiac malformations in the children of woman with gestational diabetes, possibly because this variable wasn’t included in the statistical analysis.

The authors of the study suggest two possible explanations for obesity’s important role in congenital malformations. Obesity is an indicator of energy availability and of all the nutrients that provide energy; the excess of these nutrients, and not only glucose, is linked with the appearance of malformations. In addition, both the excess and deficiency of insulin can provoke malformations in the embryo, and in the case of obesity, the fact that there is a resistance to the effects of the insulin results in higher concentrations.