Gestational diabetes mellitus and paradoxical fetal macrosomia — A case report

Abstract Gestational diabetes mellitus (GDM) is associated with an increased rate of fetal macrosomia. We describe the outcome of two pregnancies complicated by GDM occurring 2 years apart in a normal-weight woman. Despite adequate maternal blood glucose control during gestation, both infants were markedly oversized at birth (birth weight and length exceeded normal means by 3 and 2 S.D., respectively). The placental weights were far above normal. At birth, the siblings shared the typical appearance of a diabetes fetopathy. The first one developed transient, the second persistent neonatal hypoglycemia associated with hyperinsulinemia, that needed treatment with diazoxide for 2.5 months. Both infants normalized their growth rates during the following months; their psychomotor development assessed at 2 years and at 9 months of age, respectively, was normal. During the last trimester of the second pregnancy, the plasma concentration of placental lactogen (PL) increased to a very high level (19 μg/1). The maternal early insulin response to glucose increased significantly with gestation and was much above that in the non-pregnant state. This rise in insulin response could not compensate for the concomitant decrease in insulin sensitivity as assessed by the minimal model according to Bergman [2]. The pronounced fetal macrosomia described cannot be attributed to GDM only. We speculate that excess activity of lactogenic hormones like PL beside glucose contribute to exaggerated fetal β-cell function with growth acceleration and neonatal hypoglycemia. This hypothesis is in accordance with in vitro evidence indicating that PL may have an important role in the regulation of the maternal and fetal β-cell mass and function.