Maternal and neonatal phytoestrogens in Japanese women during birth

OBJECTIVE: High levels of soy isoflavonoids among adult Japanese persons ar e associated with a low incidence of hormone-dependent cancers, but nothing is known about isoflavonoids in pregnancy. STUDY DESIGN: We studied 7 young healthy Japanese women at delivery by meas uring 6 phytoestrogen metabolites in maternal and cord plasma and in amniot ic fluid. RESULTS: Total maternal plasma isoflavonoid concentrations ranged from 19 t o 744 nmol/L (mean 232 nmol/L), cord plasma values ranged from 58 to 831 nm ol/L(mean 299 nmol/L), and amniotic fluid values ranged from 52 to 779 nmol /L (mean 223 nmol/L). Maternal and cord plasma and amniotic fluid lignan va lues were low. CONCLUSIONS: The high levels of isoflavonoid phytoestrogens found in health y neonatal Japanese infants indicate transfer of isoflavonoids from the mat ernal to the fetal compartment. These compounds may modify estrogen metabol ism and action during fetal life and perhaps affect cancer risk.