Retinal maturation is delayed by repeated, but not single, maternal injections of betamethasone in sheep

Purpose The safety and efficacy of prescribing a single maternal course of corticosteroid during pregnancy has been documented in human trials. Howeve r, the current trend is to prescribe repeated courses of corticosteroid. We investigated an aspect of the safety of this practice in an animal model. Methods Date-mated ewes received saline, single or four corticosteroid inje ctions between days 104 and 124 of gestation (term = 150). Lambs were deliv ered on day 125 or 145 by caesarian section after spinal anaesthesia. Eye d iameters were measured and semi-thin toluidine-blue-stained transverse sect ions of retinae were analysed using an Optimus Image Analysis program. Results At 125 days, retinal measures in the ventral periphery and area cen tralis were significantly thinner than control (p = 0.0001). At 145 days, t otal eye size was significantly reduced compared with control (p = 0.03), a nd retinal measures in the ventral periphery (p = 0.0001), but not the area centralis (p = 0.19), remained significantly different from control. Conclusion Repeated maternal administration of corticosteroid may affect re tinal maturation in the fetus.