Impact of antenatal corticosteroids in preterm neonates based on maternal body mass index

Antenatal corticosteroids, maternal body mass index and infant morbidity within the ASTEROID trial

BACKGROUND

Antenatal corticosteroids (ACSs) administered to women before preterm birth improve neonatal health. Proportionately more women are obese or overweight in current obstetric populations than those who were included in the original trials of ACSs, and it remains uncertain if higher doses are required for such women.

AIM

Our aim was to assess the association between maternal body mass index (BMI) and infant morbidity after the administration of ACSs.

METHODS

In the secondary analysis of the ASTEROID trial cohort, women at risk of preterm birth at <34 weeks' gestation were randomised to betamethasone or dexamethasone. Infant outcomes were compared according to whether women were of normal weight (BMI < 25 kg/m² ), overweight (BMI 25-29.9 kg/m² ) or obese (BMI ≥ 30 kg/m² ).

RESULTS

Of 982 women with a singleton pregnancy and BMI data, 519 (52.9%) were of normal size, 241 (24.5%) were overweight and 222 (22.6%) were obese. Compared with infants born to women of normal weight, there was little or no difference in respiratory distress syndrome in infants born to women who were overweight (odds ratio (OR) = 0.92, 95% confidence interval (CI) 0.57, 1.49) or obese (OR = 1.44, 95% CI 0.90, 2.31). Similarly, there were no significant differences between infants born to women in the three BMI groups for other morbidities, including bronchopulmonary dysplasia, mechanical ventilation, intraventricular haemorrhage, retinopathy of prematurity, patent ductus arteriosus, necrotising enterocolitis, perinatal death or combined serious morbidity.

CONCLUSIONS

Maternal body size is not associated with infant morbidity after ACS exposure. Dose adjustment for women with higher BMI is not required.

Recent advances in our understanding of the mechanisms of lung alveolarization and bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common cause of morbidity and mortality in preterm infants. A key histopathological feature of BPD is stunted late lung development, where the process of alveolarization-the generation of alveolar gas exchange units-is impeded, through mechanisms that remain largely unclear. As such, there is interest in the clarification both of the pathomechanisms at play in affected lungs, and the mechanisms of de novo alveoli generation in healthy, developing lungs. A better understanding of normal and pathological alveolarization might reveal opportunities for improved medical management of affected infants. Furthermore, disturbances to the alveolar architecture are a key histopathological feature of several adult chronic lung diseases, including emphysema and fibrosis, and it is envisaged that knowledge about the mechanisms of alveologenesis might facilitate regeneration of healthy lung parenchyma in affected patients. To this end, recent efforts have interrogated clinical data, developed new-and refined existing-in vivo and in vitro models of BPD, have applied new microscopic and radiographic approaches, and have developed advanced cell-culture approaches, including organoid generation. Advances have also been made in the development of other methodologies, including single-cell analysis, metabolomics, lipidomics, and proteomics, as well as the generation and use of complex mouse genetics tools. The objective of this review is to present advances made in our understanding of the mechanisms of lung alveolarization and BPD over the period 1 January 2017-30 June 2019, a period that spans the 50th anniversary of the original clinical description of BPD in preterm infants.