MATERNAL AND FETAL LEVELS OF METHIONINE AND HOMOCYSTEINE IN EARLY HUMAN-PREGNANCY

Objective To investigate methionine metabolism during normal human emb ryonic development by measuring levels of methionine and total homocys teine in samples of maternal serum, extra-embryonic coelomic fluid, an d amniotic fluid. Design Cross-sectional observational study. Setting Collaboration between St Bartholomew's Hospital, London, and the Unive rsity Hospital of Nijmegen in The Netherlands. Participants Twenty-thr ee women with uncomplicated pregnancies between 8 and 12 weeks of gest ation before surgical termination of an ultrasonographically normal fe tus. Methods Maternal serum samples were collected prior to surgery. S amples of extra-embryonic fluid and amniotic fluids were obtained by t ransvaginal ultrasound-guided coelocentesis and amniocentesis. Methion ine was measured using an aminoacid analyser and total homocysteine by high performance liquid chromatography. Results Levels of methionine were four times higher in extra-embryonic coelomic fluid and twice as high in amniotic fluid compared with maternal serum. In contrast, the total homocysteine concentrations were much lower in both extra-embryo nic coelomic fluid and amniotic fluid than in maternal serum. All diff erences were significant (P less than or equal to 0.01). Conclusions T he comparatively high concentrations of methionine in extra-embryonic coelomic fluid and amniotic fluid, and the concomitant low levels of t otal homocysteine in these fluids, suggest a role for methionine metab olism during early human pregnancy.