Objective: To compare the effect of various dosage of dexamethasone (Dex) in accelerating fetal lung maturation and the accompanied side effects.
Method: Sixty time-bred Wistar rats were randomly assigned to one of the four groups (15 rats each group). They were given normal saline 0.8 ml (group A); Dex 0.2 mg (group B); Dex 0.4 mg (group C); Dex 0.8 mg (group D) IH, separated for 4 times on gestational day 15, 16. ten rats in each group were killed and hysterectomy were made immediately on day 17. The neonate breathing scale and their lung were observed and scored; the amniotic lamellar bodies (LB) were counted to assess the preterm fetal lung maturation. The remaining 5 rats in each group delivered naturally. The mother rats' condition in perinatal period, the birth weight of their neonates, and the structure of the livers and adrenal glands of the neonates were recorded to assess the side effects of the drug.
Results: The scores of neonatal breathing scale in group A to D were: 1.4 +/- 0.5, 3.6 +/- 0.7, 4.2 +/- 0.5, 4.5 +/- 0.5; their lung histologic maturation degree: 1.4 +/- 0.6, 3.9 +/- 0.9, 4.2 +/- 0.7, 4.4 +/- 0.6; and the account of their amniotic LB were: (8.6 +/- 3.0), (30.2 +/- 4.2), (33.0 +/- 3.4), (35.8 +/- 2.7) x 10(9)/ml respectively. All the indexes in the three Dex groups were higher than group A, and there were no statistical difference among in the three Dex groups except the neonatal breathing scale scores, which were higher in the high dose group D than the low dose group B. When high dose Dex was used, there was a reductive tendency in mother rats weight and its ability to resist infectious disease; meanwhile, the birth weight of their neonates reduced, the number of stillbirth and neonate liver necrosis increased.
Conclusion: By the preterm gravid rat model, low dosage of antenatal dexamethasone administration accelerate fetal lung maturation to the extent equally to the middle even high doses of the drug. When high dosage of Dex was administered, the increasing side effects on the mother rats and their fetuses were accompanied.