Fetal complications of GDM
Untreated, moderate or severe gestational diabetes mellitus (GDM) increases the risk of fetal and neonatal complications, and the risk of congenital malformations is slightly increased in infants of mothers with GDM compared to the general population. Maternal obesity increases the risk of gestational diabetes and is an independent risk factor for perinatal complications. There is a positive correlation between maternal blood glucose levels and increased birth weight, and the risk of macrosomia can be reduced by treating glucose levels during pregnancy.
Gestational diabetes is associated with an increased risk of macrosomia, perinatal complications, and a small increase in the risk of congenital malformations. Maternal obesity is often associated with GDM and is in itself an independent risk factor for perinatal complications, and macrosomia is the main factor linked to perinatal complications in GDM.
Untreated moderate or severe GDM increases the risk of fetal and neonatal complications.
The risk of congenital malformations is slightly increased in infants of mothers with GDM compared to the general population. GDM comprises two type of diabetes: (1) diabetes strictly related to pregnancy with no increased risk of congenital malformations, and (2) diabetes diagnosed during pregnancy but preexisting before pregnancy with similar risk of congenital malformations to that of preexisting diabetes (3-7%).
Thus, increased risk is of congenital malformations is associated with the presence of undiagnosed type 2 diabetes among women with GDM . A relationship exists between the risk of congenital malformations, maternal blood glucose levels, gestational age at diagnosis of diabetes and maternal obesity, all of which are found in type 2 diabetes. The pattern of congenital malformations is similar to those reported in preexisting diabetes.
Birth Weight and Adiposity
There is a positive correlation between maternal blood glucose levels, increased birth weight, and neonatal adiposity. This relationship is probably due to fetal hyperinsulinism secondary to maternal hyperglycemia. Maternal overweight and obesity is an additional risk factor for macrosomia. Intervention studies have demonstrated that treatment of GDM reduces the incidence of macrosomia .
The increased risk of perinatal death associated with GDM seems attributable to undiagnosed type 2 diabetes . Maternal obesity is often associated with type 2 diabetes or GDM and is an additional risk factor for perinatal death.
Birth injuries and brachial plexus injuries are rarely associated with GDM and an increased risk of birth injuries due to untreated GDM has not been demonstrated. The absolute risk is low and mainly associated with macrosomia.
It is not possible to establish a link between GDM and neonatal respiratory problems due to insufficient data.
The risk of neonatal hypoglycemia is difficult to quantify in the absence of a consensual definition. However, the incidence of hypoglycemia requiring intravenous therapy is low (5%).
The risks of hypocalcaemia and hyperbilirubinemia are similar to the general population.
Summary of Perinatal Complications
- The risks of perinatal asphyxia and perinatal mortality are not increased in infants born to mothers with GDM.
- Birth injuries and brachial plexus injuries are rare.
- It is not possible to establish a link between GDM and neonatal respiratory problems due to insufficient data.
- The risk of neonatal hypoglycemia is difficult to quantify in the absence of a consensual definition, but the incidence of hypoglycemia requiring intravenous therapy is low.
- The risks of hypocalcemia and hyperbilirubinemia are similar to the general population. Serious perinatal complications specifically associated with GDM are rare.
^ Sheffield JS et al. Maternal diabetes mellitus and infant malformations. Obstet Gynecol 2002; 100: 925-30.
^ Ehrenberg HM et al. The influence of obesity and diabetes on the prevalence of macrosomia. Am J Obstet Gynecol 2004; 191: 964-8.
^ Horvath K et al.l. Effects of treatment in women with gestational diabetes mellitus: systematic review and meta-analysis. BMJ 2010; 340: c1395.
^ Cundy T et al. Perinatal mortality in Type 2 diabetes mellitus. Diabet Med 2000; 17: 33-9.