Despite the proven benefits of antenatal steroids, there are still controversies regarding their use. Dexamethasone and betamethasone Dexamethasone and betamethasone are the corticosteroids recommended for antenatal therapy. These compounds have similar biologic activity, readily cross the placenta, have no mineralocorticoid activity, and have relatively weak immunosuppressive action. For the last two decades, there has been no preference between the two, but a recent study suggests that betamethasone might be the better choice. There was a trend toward increase in this adverse neurologic outcome among infants exposed antenatally to dexamethasone.
Timing is an important element in the effectiveness of antenatal corticosteroid treatment.
Strong evidence supports the benefits of antenatal steroids starting at 24 hours and lasting at least 7 days after treatment. There is a demonstrable reduction in morbidity and mortality even when antenatal steroids are given less than 24 hours before delivery. As timing of delivery varies, corticosteroids should be used whenever preterm delivery is expected. There is insufficient evidence to establish a continued effect of antenatal steroids after 7 days. For this reason, some perinatal centres repeat the dose of corticosteroids if preterm delivery is still expected.