Diabetes and diet in pregnancy.

The mean additional energy requirement for pregnancy has been calculated at 285 kcal daily and it reflects the energy needs for production of the fetoplacental unit and for the maternal physiological adaptations to pregnancy. In practice there is considerable variation in energy requirement due to alterations in maternal energy expenditure. Optimal energy intakes are dictated also by the pre-pregnancy maternal weight. The outcome of pregnancy is improved in the underweight mother by an intake which produces a weight gain in pregnancy of approximately 14 kg, whereas a rise of only 7 kg may be optimal for the obese mother. Obesity with or without diabetes is associated with macrosomia and other problems and it is sensible to attempt to limit weight gain in pregnancy at a time when maternal motivation is high. Diabetes in pregnancy may arise in patients with pre-existing NIDDM or IDDM, but more commonly it is diagnosed for the first time during pregnancy and it usually disappears after delivery (gestational diabetes). Recent evidence suggests that gestational diabetes has a strong genetic component and is usually NIDDM precipitated early in life by the pregnancy. Both gestational diabetes and NIDDM are characterized by insulin deficiency and by insulin resistance. Long-term follow-up studies have demonstrated that NIDDM or impaired glucose tolerance develop in later life in 50-70% of women with previous gestational diabetes. The adverse effects of pregnancy on the mother with pre-existing diabetes may be minimized by good diabetic control as may be adverse effects on the fetus and neonate of diabetes in the mother. An increased incidence of fetal malformations persists in pregnancies with pre-existing maternal diabetes. Diabetes of any form may be associated with neonatal hypoglycaemia. The aim of therapy is to produce maternal normoglycaemia throughout pregnancy by dietary measures and insulin treatment if required. Women with pre-existing diabetes should tighten their blood glucose control from before conception. Optimization of insulin therapy and diet are required for IDDM and most NIDDM women will require insulin treatment in pregnancy. Gestational diabetics require diet and possibly insulin. Most pregnancies now proceed to term.