Birth measures and depression at age 31 years: the Northern Finland 1966 Birth Cohort Study.

The aim of the study was to explore whether there is an association between body size at birth measured by birth weight and ponderal index and later depression at the age of 31 years. The analyses were based on 4,007 males and 4,332 females born in 1966 in the two northernmost provinces of Finland with data on current depression measured by the Hopkins Symptom Checklist-25 questionnaire (HSCL-25) and self-reported physician-diagnosed lifetime depression at 31 years and childhood characteristics. The associations between birth measures and later depression were analysed with several confounding factors including maternal depression during pregnancy. Low birth measures did not associate with adult depression in men or women. Women with high birth weight (>or=4,500 g) had a higher risk for current depression compared to women with birth weight 3,000 g-3,499 g. Women with high ponderal index (the highest 90-95 percentiles and >or=95 percentiles) had a 1.53-1.55 higher likelihood for current depression compared with women with normal ponderal index. Based on this study, large body size at birth may be a risk factor for later depression.