RESUMO
Melatonin (MLT) shows an influence on gonadal steroid genesis, and has soporific effects. Serum MLT levels were examined during late pregnancy and 4 days after delivery in 25 women. Circulating levels of melatonin were analysed as integrated values (areas under the curve [AUC]) over 24 hours, 5 to 2 days before and 4 days after delivery. Antepartum AUCs were significantly increased compared with postpartum AUCs. Additionally, MLT levels were measured every 2 hours in a subgroup of 11 women during spontaneous labour between 08.00 and 12.00 h at a time when physiological serum MLT levels were low. Increased MLT levels were determined and compared to MLT levels measured in a previous evaluation of the antepartum AUCs. Elevated serum MLT levels during late-pregnancy and labour may influence the concentration of receptors of gonadal steroids in the gravid uterus at term and the psychic perception of painful uterine contractions during labour.
