Are adolescents who were breast-fed less likely to be overweight?
Cohort data indicate that odds of being overweight decrease as breast-feeding duration increases, at least among girls. However, sibling analyses suggest that this relationship may not be causal but rather attributable to unmeasured confounding related to mothers' choice to breast-feed, or to other childhood risk factors for overweight. Our results illustrate the utility of sibling analyses in understanding the true effect of early life exposures (such as breast-feeding) on health outcomes over time, independent of confounding factors that may not be satisfactorily controlled using traditional prospective cohort methods.
Results do not support previous studies that atypical depression is usually of moderate severity. A rating scale like the GAF, which assesses both symptom severity and impairment of functioning, may give a more complete assessment of depression severity than a symptoms rating scale (used in previous studies), which does not cover atypical features and does not assess functioning.