The association of birth order with later body mass index and blood pressure: a comparison between prospective cohort studies from the United Kingdom and Brazil.

BACKGROUND: Previous studies have found greater adiposity and cardiovascular risk in first born children. The causality of this association is not clear. Examining the association in diverse populations may lead to improved insight. METHODS: We examine the association between birth order and body mass index (BMI), systolic and diastolic blood pressure (SBP/DBP) in the 2004 Pelotas cohort from southern Brazil and the Avon Longitudinal Study of Parents and Children (ALSPAC) from Bristol, south-west England, restricting analysis to families with two children in order to remove confounding by family size. RESULTS: No consistent differences in BMI, SBP or DBP were observed comparing first and second born children. Within the Pelotas 2004 cohort, first born females were thinner, with lower SBP and DBP; for example, mean difference in SBP comparing first with second born was -0.979 (95% confidence interval -2.901 to 0.943). In ALSPAC, first born females had higher BMI, SBP and DBP. In both cohorts, associations tended to be in the opposite direction in males, although no statistical evidence for gender interactions was found. CONCLUSIONS: The findings do not support an association between birth order and BMI or blood pressure. Differences to previous studies may be explained by differences in populations and/or confounding by family size in previous studies.

Risk factors for injuries in young children in four developing countries: the Young Lives Study.

OBJECTIVE: To assess the occurrence of child injury in four developing country settings and to explore potential risk factors for injury. METHODS: Injury occurrence was studied in cohorts of 2000 children of age 6-17 months at enrolment, in each of Ethiopia, Peru, Vietnam and India (Andhra Pradesh). Generalized estimating equation models were used to explore potential risk factors for child injury. RESULTS: Occurrence of child injury was high in all countries. Caregiver depression emerged as a consistent risk factor for all types of injury measured (burns, serious falls, broken bones and near-fatal injury) across all countries. Other risk factors also showed consistent associations, including long-term child health problems, region of residence and the regular care of the child by a non-household member. CONCLUSIONS: This report provides further evidence of the importance of childhood injury in developing countries and emphasizes the importance of including infants in injury research and prevention strategies. It provides strong evidence of an association between caregiver mental health and child injury risk and contributes to the limited knowledge base on risk factors for child injury in developing countries.