ANTENATAL CORTICOSTEROID-THERAPY AND RISK OF OSTEOPOROSIS

Objective To assess the risk of maternal osteoporosis associated with antenatal corticosteroid administration for neonatal respiratory distr ess syndrome prophylaxis. Design Prospective longitudinal study. Setti ng Maternity unit of Chelsea and Westminster Hospital, London. Populat ion Fourteen pregnant women who received dexamethasone therapy for fet al lung maturation in anticipation of delivery before 34 completed wee ks of gestation. Methods Blood samples were collected before dexametha sone administration, 24 hours and 48 hours after the course of dexamet hasone, and within 24 hours of delivery. Serum levels of carboxy termi nal pro-peptide of type I pro-collagen (PICP) were measured to monitor the rate of bone formation, and serum levels of cross-linked carboxy terminal telopeptide (IC:TP) were measured as a marker of bone resorpt ion. Main outcome measures Changes in the markers of bone turnover fol lowing dexamethasone administration. Results Serum PICP levels dropped 24 hours after dexamethasone therapy (P = 0.001), but partially recov ered by 48 hours (P = 0.014) to reach higher than pre-therapy levels a t delivery (P = 0.044). Although there were no corresponding changes i n the serum levels of ICTP after 24 and 48 hours of therapy, levels in creased from pretherapy to delivery (P = 0.006). Conclusion Antenatal corticosteroid therapy leads to a transient suppression of, followed b y an increase in, bone formation without any significant alteration in the pattern of bone resorption expected during pregnancy.