The causes of low oestrogen excretion in pregnancy: assessment of the fetal contribution by steroid measurements post partum.

Oestrogen levels in urine from 21 normotensive and 13 hypertensive pregnant women were moderately correlated (r = 0.48) with levels of 3 beta-hydroxy-5-ene steroids (oestrogen precursors) in urine from their infants. In five infants from otherwise normal pregnancies in which oestrogen excretion was very low, levels of 3 beta-hydroxy-5-ene steroids were significantly lower than normal while there was no difference between hypertensives and normals. Levels of urinary cortisol metabolites in the infants were moderately correlated with 3 beta-hydroxy-5-ene steroids (r = 0.55) and were especially low in 2 out of 5 infants in the series suffering from distress during delivery. We conclude that subnormal fetal steroidogenesis rather than reduced placental metabolism is the most common cause of low oestrogen excretion of unknown aetiology. A factor in the increased perinatal risk in this group may be an associated insufficient cortisol synthesis by the fetus.