Obesity and gestational diabetes in pregnancy: an evolving epidemic

Worldwide, more than one-in-three adults and one-in-four children are overweight or obese and this problem has more than doubled since 1980 [1, 2]. Obesity is not only adversely affecting world health but is also profoundly challenging economic, political, and cultural activity and function on an international level. As the obesity epidemic grows, we have an ever increasing need to understand and manage this problem (and its comorbidity of gestational diabetes) in pregnancy. Overt and measurable harm associated with maternal obesity and gestational diabetes (GDM) includes both maternal and perinatal morbidity and mortality [3, 4]. Articles in this issue provide insights into some of the clinical associations and etiological mechanisms of the adverse outcomes associated with these conditions. These insights may suggest clinical strategies to help prevent or diminish the probability of maternal and perinatal harm.

For example, Trojner-Bregar et al., demonstrate that the rate of cesarean section is increased both by increased pre-pregnancy weight and also with increasing weight gain in pregnancy [5]. This suggests clinical strategies that reduced maternal weight before achieving pregnancy and limiting weight gain in pregnancy could reduce the need for cesarean sections.

Tul et al., document population-based maternal weight gain in pregnancy and compare this to the Institute of Medicine (IOM) recommendations [6]. They found LGA infants were more common in overweight and obese mothers and were associated with weight gain greater than recommended by the IOM. SGA infants were seen more frequently in underweight and normal weight mothers who gained less weight than the IOM recommended. The greatest frequency of achieving normal weight neonates for underweight and normal weight mothers was associated with gaining the IOM recommended weight in pregnancy. However, the best chance for normal weight newborns in the overweight and obese mothers was seen in the group that gained less weight than IOM recommended for this group.

While documenting biologic and biochemical characteristics of a Mediterranean population with GDM, Savona-Ventura et al., found increased maternal age, increased pre-pregnancy weight, and increased weight gain in pregnancy were seen in the GDM group [7]. The implication that pre-pregnancy weight loss could reduce the incidence of GDM is supported by this study. The previously noted finding of higher triglycerides in the GDM group suggests mechanisms of pathophysiology and potential interventions to improve clinical outcomes [8].

The association of pre-existing obesity with adverse maternal and perinatal outcomes suggests pre-pregnancy intervention to normalize weight could be an effective preventive measure in reducing obesity related obstetric morbidity. To achieve this weight reduction, bariatric surgery using the Roux-en-Y procedure was used to treat women before pregnancy in the study by de Alencar Costa et al. [9]. This therapy was associated with decreased macrosomia, decreased GDM, and decreased pre-eclampsia. Women without the bariatric surgery had an increased incidence of preterm birth associated with the diagnosis of preeclampsia. However, this bariatric surgery was associated with anemia complicating pregnancies that followed it without decreasing the rates of cesarean sections.

Because GDM can be diagnosed and treated, screening and testing for GDM is an integral part prenatal care [10]. Innovative analysis of these tests may be useful in understanding and predicting risks and outcomes for a pregnancy. Topcu et al., found this to be true for maternal hypoglycemia noted at the 50 g glucose challenge screening [11]. This was seen more often in mothers with younger age, lower weight and lower parity, and predicted pregnancies with lower cesarean section rates, less premature deliveries, less polyhydramnios, less macrosomia and less birth trauma. Sukur et al., evaluate the relative value of the third hour glucose measurement and show omission of this component of the 100 g oral glucose tolerance test would lead to false negative tests in 10.8%–13.9% of GDM cases [12].

As obesity in pregnancy and its companion, GDM, become progressively more frequent, the level of understanding and nuanced management of these conditions becomes progressively more important. As a group, findings in these articles, and others like them, can help us identify risks and provide guidance for optimizing pre-pregnancy and prenatal care for our patients.