Race and neonatal respiratory morbidity in the late preterm period

Prematurity is one of the leading causes of perinatal morbidity and mortality. Some studies suggest that respiratory disease may differ by race in early preterm infants. However, the role of race in late preterm neonatal morbidity is not yet established.

The objective of our study was to determine whether neonatal respiratory morbidity differs by race in neonates born late preterm.

This was a secondary analysis of a randomized trial of women at high risk for late preterm delivery (Antenatal Late Preterm Steroids). Our study was limited to women with nonanomalous, singleton gestations, delivering between 34+0 to 36+6 weeks. Women were categorized into 4 groups by race: Black, White, Asian, or other/mixed. The primary outcome was a neonatal composite of treatment in the first 72 hours (continuous positive airway pressure or high-flow nasal cannula >2 hours, oxygen >4 hours, extracorporeal membrane oxygenation or mechanical ventilation) or stillbirth or neonatal death before 72 hours. The secondary outcomes included severe respiratory morbidity (the primary outcome extending continuous positive airway pressure or high-flow nasal cannula to >12 continuous hours and oxygen to at least 24 continuous hours), respiratory distress syndrome, transient tachypnea of the newborn, apnea, neonatal intensive care unit admission, bronchopulmonary dysplasia, and surfactant administration. The primary and secondary outcomes were assessed in the active (steroid) and placebo groups separately. We fit a logistic regression model to adjust for confounders related to respiratory morbidity.

Of a total of 2331 included women, 26.9% (n=627) were Black/African American, 57.1% (n=1333) White, 3.56% (n=83) Asian, and 12.36% (n=288) were other/mixed. In the placebo group, the rate of the primary outcome was significantly higher in Whites (18.6%) and Asians (22.8%) compared with the African American/Black group (12.3%) (P=.03). Adjusting for confounders, the primary outcome was not significant between the groups. The primary predictor for respiratory morbidity was a prior pregnancy with neonatal respiratory morbidity. Findings were similar in the steroid group, but severe respiratory morbidity was less common in Black infants compared with White infants (adjusted odds ratio, 0.45; 95% confidence interval, 0.24-0.83). However, a prior pregnancy with neonatal respiratory complications was no longer associated with respiratory morbidity after receipt of betamethasone.

Late preterm respiratory morbidity was similar between racial groups. Although a history of pregnancy with previous neonatal respiratory disease is the strongest risk factor for recurrence, this risk factor is mitigated by the receipt of steroids.