Comparison of maternal serum and urinary oestrogen determinations as indicators of fetal well-being.

Serum oestrogen concentration and urinary oestrogen excretion were measured in 134 women in the last trimester of pregnancy. An automated fluorimetric method was used for urinary oestrogens and a radioimmunoassay which measures both free and conjugated oestrogens, with the exception of sulphates, was employed for serum. Pregnancies were classified into a 'normal' or 'abnormal' group according to the clinical state of the baby at birth. The range of values for both serum and urinary oestrogens was wide at each stage of gestation and the mean values in the two groups were not significantly different. It was concluded that for a valid indication of fetal well-being serial determinations were essential, and that serum and urinary oestrogens were of comparable predictive value. Expressing the urinary results in terms of creatinine excretion did not improve their predictive value.