I am an endocrinologist with interest in pregnancy and saw your post. Thought this might be helpful:
Steroids may actually improve the chances of successful pregnancy.
Dexamethasone does cross the placenta. Hydrocortisone and some other steroids do not. The choice of agent depends on scenario.
If the fetus is at risk of CAH then a steroid that crosses the plaenta is desirable to inhibit excessive fetal androgen poduction and therefore reduce risk and symptoms.
If the risk of fetal CAH is low or zero (non-carrier father) then a steroid that does not cross the placenta is used to reduce maternal androgen production and minimse the effects of maternal hyperandrogenaemia on the fetus.
