Size at birth and mental health problems at 11 years of age in a Brazilian birth cohort

The aim of this study was to evaluate the association between size at birth and mental health problems at 11 years of age in the 1993 Pelotas (Brazil) Birth Cohort Study. Newborns were weighed and measured, and anthropometric indices were calculated. At 11 years of age, mental health problems were assessed using the Strengths and Difficulties Questionnaire (SDQ). Prevalence of mental health problems was 32% (95% CI: 31-33). After adjusting for potential con-founders, newborns with weight and body mass index (BMI) for age z-scores < -2 SD were at 27% (95% CI: 7-49) and 29% (95% CI: 10-51) greater risk, respectively, of developing mental health problems at age 11 years than those born with normal scores. Newborns with BMI and head circumference for age z-scores > +2 SD were at 34% (95% CI: 6-71) and 19% (95% CI: 1-40) greater risk, respectively, of developing mental health problems than those with normal scores. The results suggest that early factors that are reflected as size measurements at birth can cause mental health problems later in life.