Insulin levels in amniotic fluid of normal and abnormal pregnancies.

The normal level of insulin in amniotic fluid between the 13th and 42nd weeks of pregnancy was determined by means of 988 single analyses in individual healthy women. Insulin passes into the amniotic fluid via the fetal urine, and its level does not depend on fetal gender. Between the 13th and 25th weeks of gestation, the insulin level increases by an average of 1.3 to 5.1 microU/ml. From the 27th to the 42nd weeks, an increase of 6 to 9.1 microU/ml is observed. In the same period, the 97th percentile rises from 11.2 to 18 microU/ml. In 543 patients with pregnancy disorders, lower levels of insulin in amniotic fluid were observed in intrauterine fetal death, placental insufficiency, fetal growth retardation, and malformations. Elevated levels of insulin were observed in rhesus disease. In the treatment of pregnant women with betamimetics and glucocorticoids, the mean amniotic fluid insulin level rose to more than double the normal values.