Timing of antenatal corticosteroid administration and survival in extremely preterm infants: a national population-based cohort study.

OBJECTIVE

To explore the association between administration-to-birth interval of antenatal corticosteroids (ACS) and survival in extremely preterm infants.

DESIGN

Population-based prospective cohort study.

SETTING

All obstetric and neonatal units in Sweden from 1 April 2004 to 31 March 2007.

POPULATION

All live-born infants (n = 707) born at 22-26 completed weeks of gestation.

METHODS

The relationship between time from first administration of ACS to delivery and survival was investigated using Cox proportional hazards regression analysis.

MAIN OUTCOME MEASURES

Neonatal (0-27 days) and infant (0-365 days) survival, and infant survival without major neonatal morbidity (intraventricular haemorrhage grade ≥ 3, retinopathy of prematurity stage ≥ 3, periventricular leukomalacia, necrotising enterocolitis, or severe bronchopulmonary dysplasia).

RESULTS

Five-hundred and ninety-one (84%) infants were exposed to ACS. In the final adjusted model, infant survival was lower in infants unexposed to ACS [hazard ratio (HR) = 0.26; 95% confidence interval 0.15-0.43], in infants born <24 h [HR = 0.53 (0.33-0.87)] and >7 days after ACS [HR = 0.56 (0.32-0.97)], but not in infants born 24-47 h after ACS [HR = 1.60 (0.73-3.50)], as compared with infants born 48 h to 7 days after administration. The findings were similar for neonatal survival. Survival without major neonatal morbidity among live-born infants was 14% in unexposed infants and 30-39% in steroid-exposed groups, indicating that any ACS exposure was valuable.

CONCLUSIONS

Administration of ACS 24 h to 7 days before extremely preterm birth was associated with significantly higher survival than in unexposed infants and in infants exposed to ACS at shorter or longer administration-to-birth intervals.

TWEETABLE ABSTRACT

Timing of antenatal corticosteroids is important for extremely preterm infants' survival.