Sex Differences in Wheezing During the First Three Years of Life After Delivery via Caesarean Section.

BACKGROUND

Emerging evidence suggests that delivery by caesarean section predisposes to wheezing in early childhood, but the effect may differ between boys and girls. Such sex-specific differences remain insufficiently explored to date, particularly considering the wide range of perinatal and antenatal confounding factors. In this study, we aimed to investigate sex-specific differences in the association between delivery by caesarean section and preschool wheezing.

METHODS

This is a secondary analysis of a population of 470 children (53% boys), born and cared for between August 2009 and March 2011 at the maternity services of the University Hospital of Patras, Greece. Participants were followed up regularly until the age of 36 months. Wheezing was defined as at least one episode of doctor-diagnosed wheezing per year during the surveillance period of three years. Multivariable regression models were used to explore possible associations and adjust for confounders.

RESULTS

The rate of caesarean section was 51% ( = 240). Wheezing was reported in 144 (31%) of the children. Following delivery by caesarean section, 52 of 137 (38%) of the boys and 33 of 103 (32%) of the girls developed wheezing. In the whole cohort, development of wheezing was significantly associated with male sex [odds ratio: 1.83 (95% CI: 1.22-2.75), adjusted = 0.004], but not with caesarean section or gestational age. In girls, the development of wheezing was significantly associated with caesarean section [odds ratio: 2.48 (95% CI: 1.28-4.83), adjusted = 0.007]. In boys, the development of wheezing was not significantly associated with delivery by caesarean section.

CONCLUSIONS

Girls born by caesarean section developed wheezing more frequently than their vaginally born counterparts during the first three years of life. Although male sex proved an overall predisposing factor to preschool wheezing, boys born by caesarean section were not diagnosed with wheezing more frequently than those delivered vaginally.