There was a heated discussion earlier this year at Neonatal Doc which turned offensive and resulted in the blog's slow death as well as the deletion of some comments regarding antenatal steroids. Oddly, the topic of antenatal steriods--which remains under research and debate---had not been covered in the neonatology blogosphere that I know of.
Let me try and summarize the gist of the debate on antenatal steriods from a cursory reading of the literature. For at least ten years there has been considerable debate on what type of corticosteroid therapy is most effective and safe in improving neonatal outcomes. The efficacy and safety of a "single repeat dose" of antenatal steroids---generally betamethasone, administered in two, repeat 6 mg shots, 12 hours apart---is unchallenged.
As doctor Roger Newman, past president of the Society of Maternal Fetal Medicine, proudly told me in an interview a few months ago, "a single course of antenatal steriods has saved as many lives as the discover of penecllin in its era." Yet he admitted the jury is still out on several major questions, including the efficacy of antenatal steriods for twin pregnancies as well as the efficacy and safety of administering multiple doses---which have been administered to women who go into preterm labor early but do not deliver.
Because the efficacy of the steroids appears to decline after one week (although question remain), women who remain pregnant have been encouraged to have repeat doses of steriods until their ultimate delivery date. Several studies have shown that three or more courses of antenatal steroids can have significant detrimental effects on fetal growth, fetal weight and length, and most importantly head circumference. As such, debate remains about the best time to initiate steriod therapy and when best to end it, to maximize its benefits but minimize the potential harm to fetal development.
An article in the April 2007 issue of Pediatrics by C Bonnano, K Fuchs, and RJ Wapner offers caution. Effectively it shows that while a single or a "rescue" course of antenatal steroids is efficacious, these effects must be tempered against adverse effects seen for 4 or more courses of steroids (these would be given if, for instance, a woman remained pregant for several more months after first going into labor and receiving a dose of steroids at perhaps 22 weeks). Moreover, further evidence about the 24 month neurological and developmental outcomes for infants treated with repeat doses of antenatal steriods is still lacking.
A recent Cochrane Database article indicates that repeat doses of corticosteriods were associated with reduced risk neonatal lung disease (primarily RDS), as well as reduced birthweight and/or head circumference. They too call for caution and studies analyzing long term outcomes of infants treated with repeat doses of antenatal steriods.
It is good news that researchers are calling for caution. Perhaps they hope to avoid the recent debacle in postnatal steriod therapy for premature infants---where the use of dexamethasone was later shown to have profoundly deleterious effects including higher rates of CP and other neurological damage.
Click here for the Cochrane Database abstract.