Hypoglycaemia in pregnancy.

Normally there is a very close relationship between maternal and fetal glucose concentrations during both early and late gestation. Maternal hypoglycaemia during pregnancy will therefore not only affect the mother herself but also the conceptus. As can be judged from the literature, acute hypoglycaemic episodes are only rarely seen in non-diabetic pregnancies. In recent years it has become increasingly evident that insulin-dependent diabetic patients, whether pregnant or not, run a much increased risk of having severe hypoglycaemia (SH) attacks (i.e. the patient needs the assistance of another person to relieve the attack) whenever attempts are made to introduce tight blood glucose control. Very high incidence rates of SH between 19% and 44% have been reported in diabetic pregnancy. Episodes of SH could have serious consequences; neuroglycopenia seems especially hazardous for the mother particularly during the performance of a critical task like driving a car. While hypoglycaemia has embryopathic effects in rodents, there are no data in the human to support a teratogenic effect. Insulin-induced hypoglycaemia in the last trimester of diabetic pregnancy may increase fetal body movement and decrease the fetal heart rate variability. A number of very rare conditions such as insulinoma, severe malaria, HELLP syndrome (haemolysis, elevated liver enzymes, low platelet count), severe fulminating liver disease, and ACTH and/or growth hormone deficiency have been reported to be associated with SH. Relative hypoglycaemia--i.e. low fasting blood glucose and 'flat' glucose tolerance test--is frequently seen in normotensive pregnant women with intrauterine fetal growth retardation. This pattern of maternal carbohydrate metabolism could lead to fetal hypoglycaemia and hypoinsulinaemia and contribute to poor fetal growth.