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Sir,

We read with interest the paper on the repeated doses of antenatal corticosteroids by Brocklehurst et al. (Vol 106, September 1999)1. The authors quote animal studies that suggest possible detrimental effects to both mother and fetus with the use of repetitive courses of corticosteroids, but human data have also raised concerns that relate to a transient increase in bone resorption2 and osteonecrosis of the maternal femoral head3. In addition, a recent Australian cohort study of 477 preterm neonates reported that fetal growth restriction occurred in 9% of babies4 whose mothers were given repeated doses of corticosteroids antenatally. According to Brocklehurst et al., more than half of the indications for repeating the course of corticosteroids occurred in women with multiple pregnancies. However, the evidence to justify the use of even a single course of corticosteroids in women with higher order pregnancies in order to reduce the incidence of neonatal respiratory distress syndrome is conflicting5,6. Nor is there strong evidence for the efficacy of antenatal corticosteroid use between 24 and 28 weeks' gestation to prevent respiratory distress syndrome7. Furthermore, it was not clear from this paper whether the decision to prescribe repeated doses of corticosteroids was made by consultants, junior staff or according to local labour ward protocols. The authors have suggested a prospective, randomised trial of single versus multiple courses but in view of the potential dangers of multiple courses can such a study be ethically feasible? Another fundamental problem of trials of the duration of efficacy of antenatal corticosteroids is the confounding effect of increasing gestation which in itself is protective against the development of neonatal respiratory distress syndrome. The authors correctly conclude that confusion exists with regard to the number of doses of antenatal corticosteroids that obstetricians should use — would they like to provide a recommendation until the results of planned trials are available?

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