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Objective To determine the sex‐specific diaphragm thickness in infants with bronchopulmonary dysplasia (BPD) as well as in healthy term and near‐term infants. Methods We performed a secondary analysis of an observational study to compare the sonographic diaphragm thickness at end expiration (DT exp ) in female and male infants. The study included infants with BPD and healthy near‐term and term infants. To account for differences in anthropometric measurements, we calculated the DT exp as a ratio of body surface area (BSA). Statistical analysis was performed using R statistical software. Results Of the 111 infants included, 54 (48.6%) were female. There were no significant differences in mean (SD) birth gestation 26.2 (2.1) vs 26.3 (2.1) weeks and mean study age 38.0 (2.0) vs 37.4 (1.1) weeks of male vs female infants with BPD. The mean (SD) DT exp 1.5 (0.4) mm vs 1.2 (0.3) mm, P = .02 and DT exp /BSA 8.3 (2.3) mm/m 2 vs 6.7 (1.6) mm/m 2 , P < .01 were significantly thicker in female than male infants with BPD. In contrast, there were no significant differences in DT exp between sexes 1.5 (0.4) mm vs 1.5 (0.3) mm, P = .89 within the healthy control group. Moreover, there were no differences in inspiratory diaphragm thickness, diaphragm thickness fraction, or excursion between males and females in the BPD or healthy groups. Conclusions Male infants with BPD exhibit thinner diaphragm thickness compared with female infants. Its implication on higher rates of BPD in preterm males is unclear, but this finding highlights the need for further investigation.
Yeung et al. (Tue,) studied this question.