Oestrone, oestradiol and oestriol glucosiduronates and sulphates in human puerperal plasma and milk

Conjugated and unconjugated oestrone, oestradiol and oestriol were measured in simultaneous milk and plasma samples obtained from 21 women in the early post-partum period. Conjugated oestrogens comprised more than 90% of the total oestrogen content of both milk and plasma. Oestrone glucosiduronate was the major oestrogen metabolite in milk (33%), the levels being significantly higher (P less than 0.01) than in plasma. Oestriol glucosiduronates were the predominant oestrogen metabolites (63%) in plasma.