[Effect of pregnancy and labor on serotonin metabolism].

Several complications of pregnancy have been reported to be associated with alterations of serotonin (5-hydroxytryptamine; 5-HT) metabolism. Reported data regarding changes of 5-HT metabolism in pregnancy are partially contradictory. The presented study tries to describe pregnancy-associated changes in 5-HT metabolism. Urine and blood samples were taken from 20 pregnant women 4 weeks before, within 24 hours and on the 4th day following delivery. 17 non-pregnant age-matched women served as controls. 5-HT and its main metabolite 5-hydroxyindoleacetic acid (5-HIAA) were analysed. We observed a continuously increasing production and excretion of unbound 5-HT and 5-HIAA during pregnancy. Four days after delivery 5-HT production returned to baseline levels, while excretion remained elevated. 5-HIAA excretion increased in pregnancy and return to baseline levels on the day following delivery. Increased 5-HT metabolism and excretion results in a decreased 5-HT serum concentration despite increased 5-HT production during pregnancy. Our results help to understand the contradictory observations of elevated 5-HT production on the one hand and decreased 5-HT activity during pregnancy on the other.