Male sex associated with higher iron deficiency and rapid weight gain in healthy term infants over 6 months.

This retrospective cohort study evaluated 355 healthy term infants at a hospital in Chengdu, China, to assess the association between sex and iron status. The primary outcome was iron deficiency at 6 months, with secondary assessment of rapid weight gain. The follow-up period was 6 months.

Results indicated that male sex was associated with greater rapid weight gain compared to females, with an effect size of β = 0.61 kg and a 95%CI of 0.44 to 0.78. Iron deficiency occurred in 22.5% of the infants overall. The highest incidence of iron deficiency was observed in exclusively breastfed males, reported at 36%.

No adverse events, serious adverse events, discontinuations, or tolerability data were reported in the study. The study design is observational, meaning the observed associations between male sex, rapid weight gain, and iron deficiency cannot be interpreted as causal. Key details regarding absolute numbers for specific subgroups and p-values for the primary outcome were not reported.

Given the retrospective nature and lack of reported limitations or funding conflicts, the practice relevance remains uncertain. Clinicians should interpret these findings as associations within a specific population rather than definitive evidence for intervention.