INFANT OF A DIABETIC MOTHER
Congenital anomalies are a complications of pregestational diabetes mellitus as the fetuses are exposed to hyperglycaemia during the critical period of organogenesis. A linear relationship between HbA1c and malformation rates have been reported, with the optimal HbA1c set at below 6.1% with avoidance of troublesome hypoglycaemic symptoms. Unfortumately most anomalies occur before pregnancy is recognized, highlighting the need for optimal glycemic control at the preconception stage. The anomalies predominantly affect the cardiac, skeletal, central nervous and gastrointestinal systems.
Macrosomia, defined as a birthweight
above 90th centile commonly complicates diabetic pregnancies. This is a result of fetal hyperinsulinaemia and is associated with increased risk of shoulder dystocia, obstructed labour, instrumental delivery, birth injuries and caesarean section.
Although less common than macrosomia, fetal growth restriction could occur as a consequence of placental insufficiency especially in women with pregestational diabetes with microvascular complications.
Respiratory complications that are commonly seen among neonates of diabetic women are due to inadequate pulmonary fluid absorption caused by lack of labour induced stress hormonal surge, as elective deliveries are performed to reduce the risk of late intrauterine death.
Other adverse fetal/neonatal effects include intrauterine death, polycythaemia, jaundice, hypocalcaemia, hypoglycaemia and hypertrophic cardiomyopathy.