Antenatal corticosteroids: an updated assessment of anticipated benefits and potential risks

Abstract

Antenatal steroid therapy is increasingly central to the obstetric management of women at imminent risk of preterm birth. For women likely to deliver between 24 and 34 weeks’ gestation, antenatal steroid therapy is standard of care, conveying sizable benefits and few risks in high-resource environments when appropriately targeted.Recent studies have focused on antenatal steroid use in periviable and late preterm populations, and in term cesarean deliveries. As a result, antenatal steroid therapy has now been applied from 22 weeks, to those delivered at 39+6 weeks estimated gestational age. There is also an increased appreciation that the vast majority of randomized control data informing the use of antenatal steroids derive from predominantly high-resource, Caucasian populations. Accordingly, a sizable amount of work has recently been undertaken to test if and how to safely use antenatal steroids in low- and middle-resource environments, wherein the often-high rates of preterm birth make these low cost, easily administered interventions an attractive proposition.It is likely underappreciated by the obstetric and neonatal communities that the overall efficacy of antenatal steroid therapy is highly variable (including when preterm risk is accurately assessed), that the treatment regimens employed are largely arbitrary, dosing is supra-pharmacological for effect, and the extent to which the benefit to risk balance is significantly and differentially modified by gestation. It is also very likely that the patients consented to receive these treatments are similarly unaware of the complex balance of potential benefits and harms. Although a small number of follow-up studies present a generally benign picture of long-term antenatal steroid risk, several large, population-based retrospective studies have identified associations between antenatal steroid use, childhood mental disease and newborn infections that warrant urgent attention.Of particular contemporary importance is emergent efforts to optimize antenatal steroid regimens based on the pharmacokinetics and pharmacodynamics of the agents themselves, the need for better targeting of these potent drugs, and clear articulation of the potential benefits and harms of antenatal steroid use at differing stages of pregnancy, and in different delivery contexts.