To understand the effect of prenatal stress on sex-specific changes in embryonic and placental growth, a synthetic glucocorticoid (dexamethasone) was administered intraperitoneally at a dosage of 1 mg/kg body weight (BW) (Dex1) or 10 mg/kg BW (Dex10) to pregnant ICR mice at the gestational days 7.5, 8.5 and 9.5 post coitum (p.c.). Embryos and placentas were then harvested at days 11.5 and 18.5 p.c., and their body weight and size were measured following the determination of sex through PCR using Sry specific primers in tail tissues. As a result, female embryos presented reduced fetal body weight and size in Dex1- and Dex10-treated groups than those of control group at the embryonic day 11.5 p.c. Interestingly, the growth seems to be recovered at day 18.5 as there was no difference in growth between control and dexamethasone treated groups. In the case of males, Dex1 induced a decrease in fetal weight in day 11.5 and this pattern was maintained until day 18.5, whereas their growth was not affected by Dex10 treatment. Placental growth showed similar patterns to fetal growth in both sexes but the extent of reduction was not statistically significant in most cases. Placental weights in Dex1- and Dex10-treated group were decreased significantly in male only. The results imply that the effect of prenatal stress is largely sex dependent due to different strategies for growth and survival in a stressful environment.