Controversy: antenatal steroids

Abstract

There is no controversy that women at risk of preterm delivery before 32 to 34 weeks' gestational age should be treated with antenatal steroids. Three recent meta-analyses by the Cochrane Collaboration on the benefits of antenatal steroids, the choice of steroid and dosing, and repeat doses of corticosteroids comprehensively summarize the available clinical information to about 2007. However, there are many unanswered questions about which steroid and dose to use and about their use in selected populations. This review focuses on those areas of uncertainty.

Fig. 1

Fetal indicators of lung maturation following maternal treatments with saline (control), one dose of 0.25 mg/kg betamethasone acetate (0.25 – Beta-Ac), one dose of 0.5 mg/kg Beta-Ac, 4 doses of 0.25 mg/kg Beta phosphate (-PO₄) given at 12h intervals, or 2 doses of Celestone (0.5 mg/kg of a 1 to 1 mixture of Beta Ac and Beta-PO₄ given at a 24h interval). All fetuses were delivered prematurely 48h after the initial treatment. A) Lung compliance measured by the lung gas volume at 40 cmH₂O pressure increased for all treated groups relative to controls. B) The mRNA for the surfactant protein (SP)-B also increased in the fetal lungs. *p<0.05 vs. controls Data from Jobe, et. al. (17).

Fig. 2

Plasma levels of betamethasone (Beta), birth weights, and lung gas volumes. A) Beta levels in fetal plasma after maternal treatments with 0.5 mg/kg Beta acetate plus phosphate (maternal) or after fetal treatment with the same dose based on estimated fetal weight (fetal). B) One or 3 weekly fetal treatments with this dose did not decrease birth weight while maternal treatments decreased birth weight. C) Lung gas volume measured at 40 cmH₂O pressure as a measure of lung maturation increased more with maternal than fetal treatments. Data from Berry, et al (Frame A) (19) and Jobe, et al. (Frames B and C) (24). *p<0.05 vs. control, ^t p <0.05 – 3 doses maternal vs. 3 doses fetal