The association between fetal gender in twin pregnancies and the risk of pediatric infectious diseases of the offspring: A population-based cohort study with long-term follow up

Objective: We aimed to study the association between fetal gender in twin pregnancies and the risk for childhood infectious morbidity of the offspring. Study design: A population-based cohort analysis was performed comparing total and subtypes of infectious related pediatric hospitalizations among males versus females offspring of twin pregnancies. The analysis included all dichorionic twins born between the years 1991–2021. A Kaplan–Meier survival curve was used to compare the cumulative infectious morbidity incidence, and a Cox proportional hazards model was constructed to adjust for confounders. Results: The study population included 4222 newborns (2111 males and 2111 females). Males had higher rates of infectious-related hospitalizations using a Cox proportional hazards model, an independent association was shown between male gender and infectious related hospitalizations of the offspring (Adjusted HR = 1.2, 95% CI: 1.1–1.4; p < 0.001). Conclusion: Male gender in twin pregnancies is associated with an increased risk for long-term pediatric infectious morbidity.