Amniotic fluid glucose values in normal and abnormal pregnancies.

Glucose values were determined in 102 urine samples of newborn infants and in 2295 amniotic fluid (AF) samples of women between the 14th and 42nd week of pregnancy. One thousand, six hundred fifty-five of the AF samples derived from normal pregnancies, 50 from pregnancies with fetal malformations, 115 from cases of hydramnios, 246 from pregnant women with an abnormal oral glucose tolerance test, and 230 from insulin-dependent diabetics. Mean AF glucose concentration rises slightly between the 14th and 17th week of pregnancy, decreasing from 46 to about 16 mg% at the end of pregnancy. In cases of fetal malformations, 68% of the glucose levels was below the tenth percentile of normal values. Hydramnios showed no deviation from normal values. In patients with abnormal glucose tolerance, AF glucose increased by a total of 42% and by 67% in fetal hyperinsulinism. Insulin-dependent diabetics had glucose values elevated by a total of 77% and by 106% in fetal hyperinsulinism. The AF glucose profile reflects the level of maternal blood glucose that is transported to the fetus and excreted in the fetal urine as a major source of glucose in AF.