To investigate the role of epidermal growth factor (EGF) in feto-placental development, we measured the urinary and amniotic fluid EGF levels throughout pregnancy. Thirty urinary samples of non-pregnant women, 85 of normal pregnant women, 21 of women with toxemic pregnancy, 17 of postpartum women and 30 of newborns, and 55 amniotic fluid samples of pregnant women with a variety of conditions necessitating amniotomy and amniocentesis at 25-39 weeks of gestation were collected. EGF concentrations were measured by double-antibody radioimmunoassay. Urinary EGF levels of pregnant women reached their peak (24.6 +/- 6.7 ng/mg creatinine) at 19-22 gestational weeks; after that, they slightly decreased. Although there is no significant difference between the urinary EGF levels of non-pregnant women (19.0 +/- 5.1) and those of pregnant women (18.1 +/- 3.2), the EGF levels of toxemic women (12.2 +/- 1.5) were lower than those of normal pregnant women. The levels in puerperium women were similar to those found during pregnancy. However, the neonates had higher urinary EGF concentrations than those in pregnant women. On the other hand, EGF levels in amniotic fluid were higher according to gestational weeks and the levels of intrauterine growth retardation (IUGR) cases lower compared with normal pregnancy. Furthermore, EGF concentrations in amniotic fluid have a significant correlation with the creatinine levels in amniotic fluid. These data suggest that EGF plays an important role in fetoplacental development and it is possible that the measurement of amniotic fluid EGF might become available for the clinical assessment of fetal maturation.