Sex differences in child and adolescent physical morbidity: cohort study.

Background: Evidence on sex differences in physical morbidity in childhood and adolescence is based largely on studies employing single/few physical morbidity measures and different informants. We describe sex differences in a wide range of parent/carer-reported physical morbidity measures between ages 4 and 13 years to determine evidence for a generalised pattern of an emerging/increasing female 'excess'.

Methods: Parents/carers (approximately 90% mothers) of the population-based UK ALSPAC cohort provided data on general health, physical conditions/symptoms and infections in their child approximately annually between ages 4 and 13. Logistic regression analyses determined the odds of each morbidity measure being reported in respect of females (vs males) at each age and the sex-by-age interaction, to investigate any changing sex difference with age.

Results: Six measures (general health past year/month, high temperature, rash, eye and ear infections) demonstrated an , and six (earache, stomach-ache, headache, lice/scabies, cold sores, urinary infections) an ; one (breathlessness) showed a . Just two showed either an or 'excess'. Most changes were evident during childhood (prepuberty). Six measures showed and four '. Few measures showed no sex differences throughout this period of childhood/early adolescence.

Conclusion: Sex differences are evident for a wide range of parent-reported physical morbidity measures in childhood and early adolescence. Far more measures showed an emerging/increasing female 'excess' than an emerging/increasing male 'excess'. Further studies are required to examine whether patterns differ across sociodemographic/cultural groups, and to explain this generalised pattern.