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Giấy hội thảo lần đầu tiên xác định được một chiến lược phòng ngừa, chứ không phải là chữa, thiếu bề mặt đã được xuất bản hơn 30 năm trước đây. Các đầu mối đầu tiên đến từ những quan sát rằng con chiên thử nghiệm giao sớm thất bại trong việc phát triển các vấn đề hô hấp | BETAMETHASONE well comment Use Maternal treatment with betamethasone accelerates surfactant production by the fetal lung reducing the incidence of neonatal respiratory distress a property it shares with dexamethasone q.v. . Pharmacology The pharmacology of betamethasone and dexamethasone are very similar. See the web commentary for increasingly strong evidence that antenatally betamethasone is much safer than dexamethasone. Indications for antenatal use The seminal paper that first identified a strategy for preventing rather than curing surfactant deficiency was published more than 30 years ago. The first clue came from the observation that experimental lambs delivered prematurely failed to develop the respiratory problems seen in control animals if exposed to corticosteroids before delivery. A randomised placebo-controlled trial that eventually recruited more than a thousand mothers from New Zealand soon confirmed that two 12 mg IM doses of betamethasone caused a significant reduction in the incidence of respiratory distress in babies born more than eight weeks early and a fall in neonatal mortality in all babies born more than three weeks early. Doubling this dose brought about no further improvement in outcome. No study has ever looked to see if a smaller dose might be equally effective. It took 20 years for this strategy to gain general acceptance and in the interim a further eleven trials were done to replicate the original findings. Eventually a Cochrane review of all the trials in 1989 showed that antenatal treatment with 24 mg of betamethasone or dexamethasone was associated with a 40-60 reduction in the risk of neonatal respiratory distress independent of gender and that benefit appears to apply to babies born at all gestational ages at which respiratory distress syndrome may occur . Indeed another recently completed trial has shown that prophylaxis also reduces the risk of respiratory distress in babies delivered by elective section at 37-38 weeks .
