The main objective of this study was to evaluate the relationship between maternal infection induced by pyrogen administration and the changes in maternal and fetal plasma levels of prostaglandin E2 (PGE2) and F 2 alpha (PGF 2 alpha) and uterine contraction. We administered one mg of pyrogen (E. coli endotoxin) into the maternal femoral vein; then then the changes in maternal and fetal core temperatures, plasma levels of PGE2, [PGE2] and PGF 2 alpha, [PGF 2 alpha]. pO2, pCO2, pH and maternal uterine contractions were measured in late-gestation pregnant goats (n = 8). Maternal and fetal core temperatures were elevated significantly 30 min after pyrogen administration (p < 0.05), reached their peak levels after 3 hours, and after 5 hours mean core temperatures returned to levels indistinguishable from initial control. Maternal plasma [PGE2] and [PGF 2 alpha] increased to 4318 +/- 321 pg/ml after 1 hour and to 670.8 +/- 58.4 pg/ml after 3 hours respectively (p < 0.05). Fetal plasma [PGF 2 alpha] increased significantly (p < 0.05) to 811.0 +/- 64.0 pg/ml after 1 hour; however, plasma [PGE2] did not change throughout the study. Periodic uterine contractions appeared after 3 hours and disappeared after 5 hours. These results suggest that pyrogen induces the elevation of maternal and fetal core temperatures and prostaglandin production, and that eventually causes uterine contractions.