Newborn of a Mother With Diabetes

An infant of a diabetic mother (IDM) is a newborn exposed to maternal diabetes during pregnancy. The diabetes may be type 1, type 2 or gestational. The degree of neonatal risk depends on maternal glycaemic control, diabetes type, the timing of hyperglycaemia, placental function and other maternal-fetal factors. One mental model explains most of what follows. Before birth, the fetus lives in a high-glucose environment and adapts by making more insulin. At birth, the glucose supply stops and the insulin does not. The newborn is suddenly a well-insulinized baby with no incoming glucose. Maternal glucose crosses the placenta through facilitated diffusion. Maternal insulin does not cross the placenta in clinically significant amounts. Maternal hyperglycaemia therefore causes fetal hyperglycaemia, and the fetal pancreas responds by increasing insulin secretion. Chronic fetal hyperglycaemia may cause pancreatic beta-cell hyperplasia and fetal hyperinsulinaemia. Insulin promotes fetal growth and fat deposition, which is why macrosomia develops. The sequence runs in order: 1. Maternal blood glucose becomes elevated. 2. Glucose crosses the placenta. 3. Fetal blood glucose increases. 4. The fetal pancreas secretes more insulin. 5. Fetal...