Objective: To examine how the effect of disadvantaged socioeconomic circumstances on the risk of paediatric infections is mediated by pregnancy smoking, excess weight during pregnancy and breast feeding in children under 5 years of age.

Design: A population-level, retrospective cohort study. The Swedish Medical Birth Register was combined with the National Patient Register, the longitudinal integration database for health insurance and labour market studies, the Cause of Death Register and a local register held by the Child Health Care Unit in Uppsala Region.

Setting: Uppsala Region, Sweden.

Patients: 63 216 term and post-term singletons born to women who resided in Uppsala Region, Sweden between 1997 and 2015.

Main outcome measures: Number of hospital admissions for infectious diseases. Secondary outcomes were the number of hospitalisations for respiratory and enteric infections, respectively.

Results: The effect of disadvantaged socioeconomic circumstances, that is, low maternal education on the overall risk of paediatric infections was mediated to a considerable (33%-64%) proportion by pregnancy smoking, excess weight during pregnancy and breast feeding.

Conclusions: Pregnancy smoking, excess weight during pregnancy and breast feeding mediate a considerable proportion of the association between deprived socioeconomic circumstances and paediatric infectious diseases. Therefore, inequalities in paediatric infectious diseases may be reduced by public health policies addressing these health-related behaviours.

Objective The aim of this study was to examine this association between maternal weight during pregnancy and the incidence of hospitalisations for infectious diseases during early childhood. Design A population-based cohort study. Setting A national cohort was created by combining data from the Swedish Medical Birth Register, the National Inpatient Register, the Cause of Death Register, the Total Population Register and the Longitudinal integration database for health insurance and labour market studies. Patients 693 007 children born in Sweden between 1998 and 2006. Main outcome measures Number of hospitalisations for infectious diseases during the first 5 years of life, overall and for categories of infectious diseases (lower respiratory, enteric, upper respiratory, genitourinary, perinatal, skin and soft tissue, neurological and eye, digestive tract, bloodstream and other infections). Results Overweight (body mass index (BMI) 25.0-29.9) and obesity (BMI >= 30) during pregnancy were associated with a higher overall incidence of hospitalisations for infectious diseases, adjusted incidence rate ratio (IRR) 1.05 (95% CI 1.03 to 1.06) and adjusted IRR 1.18 (95% CI 1.16 to 1.21). Overweight and obesity during pregnancy were strongly associated with perinatal infections, adjusted IRR 1.34 (95% CI 1.25 to 1.44) and adjusted IRR 1.72 (95% CI 1.57 to 1.88). In contrast, we found no association between maternal weight during pregnancy and infections of skin and soft tissue, the nervous system, the digestive tract or the bloodstream. Conclusions We observed an association between overweight and obesity during pregnancy, and hospitalisations for infectious diseases during early childhood.

OBJECTIVE: To examine the association between breastfeeding practice and hospitalisations for infectious diseases in early and later childhood, in particular, to compare exclusive breast feeding 4-5 months with exclusive breastfeeding 6 months or more. Thereby, provide evidence to inform breastfeeding policy. DESIGN: A register-based cohort study. SETTING: A cohort was created by combining the Swedish Medical Birth Register, the National Inpatient Register, the Cause of Death Register, the Total Population Register, the Longitudinal integration database for health insurance and labour market studies, with the Uppsala Preventive Child Health Care database. PATIENTS: 37 825 term and post-term singletons born to women who resided in Uppsala County (Sweden) between 1998 and 2010. MAIN OUTCOME MEASURES: Number of hospitalisations for infectious diseases in early (<2 years) and later childhood (2-4 years). RESULTS: The risk of hospitalisations for infectious diseases decreased with duration of exclusive breastfeeding until 4 months of age. In early childhood, breast feeding was associated with a decreased risk of enteric and respiratory infections. In comparison with exclusive breast feeding 6 months or more, the strongest association was found between no breastfeeding and enteric infections (adjusted incidence rate ratios, aIRR 3.32 (95% CI 2.14 to 5.14)). In later childhood, breast feeding was associated with a lower risk of respiratory infections. In comparison with children exclusively breastfed 6 months or more, the highest risk was found in children who were not breastfed (aIRR 2.53 (95% CI 1.51 to 4.24)). The risk of hospitalisations for infectious diseases was comparable in children exclusively breastfed 4-5 months and children exclusively breastfed 6 months or more. CONCLUSIONS: Our results support breastfeeding guidelines that recommend exclusive breastfeeding for at least 4 months.

Background: It is well known that socially deprived children are more likely to be hospitalised for infections. Less is known about how different social disadvantages interact. Therefore, we examine intersectional inequalities in overall, upper respiratory, lower respiratory, enteric and genitourinary infections in the first 5 years of life.

Methods: We conducted a population-based retrospective cohort study of Swedish children born between 1998 and 2015. Inequalities were examined using analysis of individual heterogeneity and discriminatory accuracy as the analytical framework. A variable with 60 intersectional strata was created by combining information on maternal education, household income, sex/gender and maternal migration status. We estimated the incidence rates of infectious disease hospitalisation for each intersectional strata and the associations between intersectional strata and infectious disease hospitalisations using logistic regression models. We furthermore quantified the discriminatory ability of the intersectional strata with respect to infectious disease hospitalisation.

Results: The study included 1785 588 children and 318 080 hospital admissions. The highest overall incidence of hospitalisations for infections was found in boys born to low-educated mothers who lived in families with the lowest household income. The overall incidence of infections was unrelated to household income in children born to highly educated mothers. The ability of the intersectional strata to discriminate between children with and without infections was poor.

Conclusion: We found that inequalities in paediatric infectious diseases were shaped by the intersections of different social disadvantages. These inequalities should be addressed by public health policies that reach all children.