# The influence of antenatal betamethasone timing on neonatal outcome in late preterm infants: a single-center cohort study

## TL;DR

This study examines how the timing of antenatal betamethasone affects late preterm infants and finds recent administration may reduce respiratory issues in high-risk cases.

## Contribution

The study introduces a risk-adapted approach to antenatal corticosteroid use in late preterm pregnancies.

## Key findings

- Recent antenatal corticosteroid administration reduced cardiorespiratory morbidities in high-risk late preterm infants.
- The benefit of recent corticosteroid use depends on the prevalence of respiratory disease in the population.
- Current evidence supports the need for better antenatal tools to predict respiratory risks before additional steroid courses.

## Abstract

Many pregnancies continue after antenatal corticosteroid exposure. Since long-term effects on late preterm neonatal outcome remain controversial, it remains unknown whether pregnant women who are at risk for preterm birth during the late preterm period and had prior antenatal corticosteroid exposure would benefit from an additional course of antenatal corticosteroids. We evaluated the need for future trials on this topic by comparing short term effects from antenatal betamethasone to long-term effects. We also examined the value of a risk-adapted approach.

We observed neonatal outcomes in late preterm infants (34/0–36/0 weeks of gestation) who were exposed to antenatal betamethasone either up to 10 days prior birth (n = 8) or earlier in pregnancy (n = 89). We examined a real world population from the University Hospital Magdeburg (Germany) between 01 January 2012 and 31 December 2018, and a simulated high-risk population that was derived from the original data.

The indicators for relevant adverse outcomes did not differ in the unselected population. In the simulated high-risk population, recent antenatal corticosteroid administration significantly reduced the incidence of relevant cardiorespiratory morbidities (OR = 0.00, p = 0.008), and reduced the number needed to treat from 3.7 to 1.5.

The superiority of recent antenatal corticosteroid administration in the late preterm period over earlier exposure strongly depended on the prevalence of respiratory disease. Before considering clinical trials on additional antenatal corticosteroid courses in the late preterm period, antenatal assessment tools to predict respiratory morbidity need to be developed.

The online version contains supplementary material available at 10.1007/s00404-024-07714-9.