Disproportionate growth of organs and body weight following glucocorticoid treatment of the rat fetus.

The effects of pharmacologic doses of dexamethasone, betamethasone, and cortisone given to pregnant rats on gestation days 12 and 13 were studied in mothers and fetuses on gestation day 21. Dexamethasone and betamethasone treatment resulted in a significant decrease in maternal and fetal weight gain, occurrence of cleft palate and omphalocele, and impaired growth of fetal heart, liver, adrenals, kidneys, and skeletal muscle. Cortisone produced fewer developmental defects and less impairment of growth of fetal weight and other organs. Corynebacterium kutscheri infections occurred in pregnant rats treated with dexamethasone but not in rats treated with betamethasone or cortisone. The analogues had widely different effects on organ growth and on the ratios of organ weight to body weight. The findings indicate that proportionate growth of fetal organs and body weight is disturbed by glucocorticoid treatment in rats.