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Background: We aim to assess whether the docosahexaenoic acid (DHA)–containing lipid emulsion (LE) SMOFlipid 20% (Fresenius Kabi Canada Ltd) is associated with bronchopulmonary dysplasia (BPD)–free survival at 36 weeks' postmenstrual age in very preterm infants. Methods: This cohort study is nested in the MOBYDIck randomized clinical trial (NCT02371460), which investigated the effect of maternal DHA supplementation on BPD‐free survival in breastfed very preterm infants born between 23 0/7 and 28 6/7 weeks' gestation in 16 Canadian neonatal intensive care units (2015–2018). Parenteral SMOF‐LE was given to the infants according to the sites' routine care protocols. Relative risks (RRs) were estimated using a modified Poisson regression model with generalized estimating equations taking into account recruitment site, multiple birth, DHA supplementation, birth weight, sex, and gestational age. Results: Among 528 infants (mean gestational age, 26.5 weeks [SD, 1.6]), 272 received SMOF‐LE. Overall, 56.7% of the infants in the SMOF‐LE group and 59.7% infants in the non–SMOF‐LE group survived without BPD (adjusted RR, 0.94 [95% CI, 0.77–1.14]; P = 0.51). BPD rates were 39.3% in the SMOF‐LE group vs 34.1% in the non–SMOF‐LE group (adjusted RR, 1.10 [95% CI, 0.82–1.47]; P = 0.53). Severe BPD rates were 31.8% in the SMOF‐LE group vs 28.8% in the non–SMOF‐LE group (adjusted P = 0.59). Mortality was not significantly different between the SMOF‐LE (6.7%) and non–SMOF‐LE groups (9.5%; adjusted P = 0.40). Conclusion: In very preterm infants, intravenous DHA‐containing SMOF‐LE during the neonatal period was not associated with BPD‐free survival. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of the study? Is there a sex‐based difference in the incidence of apnoea of prematurity and the success or failure of caffeine therapy in preterm infants? What is the main finding and its importance? Our data show that females received fewer days of caffeine treatment than males. This was most noticeable in infants born between 260/7 and 276/7 weeks of gestational age. These results highlight the importance of considering sex in clinical and basic research investigating the pathophysiology of apnoea of prematurity. Abstract: This retrospective cohort study assessed whether sex influences the occurrence of apnoea of prematurity (AOP) in preterm infants. The analysis included a cohort of 24,387 preterm infants born between the gestational ages (GA) of 240/7 and 336/7 weeks that were admitted to tertiary neonatal care units participating in the Canadian Neonatal Network from January 2011 to December 2015. Of those, 13,983 (57%) were diagnosed with AOP. More females were diagnosed with AOP than males, but the difference in the male/female ratio was marginal (P = 0.058). The majority (89%) of infants diagnosed with AOP received caffeine (89% of males; 89% of females). By using the discontinuation of caffeine therapy as a proxy for the resolution of significant AOP, data analysis showed that females born before 336/7 weeks of GA stopped caffeine treatment earlier than males whether the caffeine was discontinued before 34 or 37 weeks of GA. Consequently, females had fewer days of caffeine therapy than males, especially infants born between 260/7 and 276/7 weeks (P < 0.004), 280/7 and 296/7 weeks (P < 0.03), and 320/7 and 336/7 weeks of GA (P < 0.04). Similar trends were observed when the corrected GA at discontinuation of caffeine was used. Given that AOP is indicative of an immature respiratory system, our data suggest that the maturation of the respiratory system might occur more rapidly in females than males. We conclude that sex needs to be considered in future studies on AOP. [ABSTRACT FROM AUTHOR]

Fetal lung growth and functional differentiation are affected strongly by the extent that pulmonary tissue is distended (expanded) by liquid that naturally fills developing future airspaces. Methods that prevent normal egress of this lung fluid through the trachea magnify mechanical stretching of lung parenchymal cells, thereby promoting lung development. Indeed, experimental observations demonstrate that in utero tracheal occlusion (TO) performed on fetuses during the late canalicular-early saccular stage potently stimulates pulmonary growth and maturation. In this review, we present the four principle non-human animal models of TO/obstruction and discuss them in relation to their utility in elucidating lung development, in remedying congenital diaphragmatic hernia (CDH) as well as in investigating the stretching effects on growth and remodeling of the fine vasculature., ((c) 2007 Wiley-Liss, Inc.)