Human fetal serum cortisol levels at delivery: a review

Abstract

A review of the data for fetal cortisol levels at delivery suggests that many of the values published over the past decade are too high owing to the use of methods insufficiently specific for cortisol in cord blood. Pitfalls in the assay of cortisol have been discussed elsewhere (40). The recent use of nonspecific methods is surprising since apparently correct values were established using DIDD in the early 1960s. The high values have mainly been associated with RIA and fluorometry, which have been shown to lack specificity in human urine as well (41). The nature of the interfering material in cord serum and urine is still not entirely clear. At least part of it probably represents cortisol metabolites. The mode of delivery and anesthetic used are also important since values obtained at elective cesarean section are lower than those after vaginal delivery. The lower values at cesarean section may be due to the decreased stress to the infant, the common use of general anesthesia, and/or lower gestational age. Gestational age is very important since values in premature infants are only about half those of mature infants, and are lower in those who go on to develop the respiratory distress syndrome.