EFFECT OF MATERNAL GLUCOCORTICOID TREATMENT ON OVINE FETAL FLUIDS AT 0.6 GESTATION

This study examined the effects of maternal dexamethasone treatment on the volume and composition of fetal fluids, and on placental morpholo gy at 0.6 gestation (80-90 days). Nine pregnant ewes were infused with dexamethasone (D, 0.76 mg h(-1) for 72 h) while an additional nine ew es received saline (S, 0.38 mL h(-1) for 72 h). Allantoic fluid (ALF) volume was significantly greater (P < 0.02) in the D group (737+/-116 mL) than in the S group (190+/-55 mL), but there was no difference in amniotic fluid (AMF) volume. The urine flow rate was 11 times higher i n three D fetuses. The Cr-51-EDTA infused into the bladders of four fe tuses during the final 4-5 h of the 72 infusions was detected in both AMF and ALE Dexamethasone treatment significantly altered the composit ion of the fetal fluids but had no affect on fetal body weight, organ weights and placental weight; however, there were fewer cotyledons und er 5 g (P < 0.05). In the D group, 3% of cotyledons were of the 'bovin e' type in morphology, whereas all cotyledons in the S group were of t he 'ovine' type. These findings suggest that prolonged exposure to lar ge doses of glucocorticoids during pregnancy would affect the volume a nd composition of the fetal fluids and placental morphology, with pote ntially detrimental effects on the fetus.