Health selection among migrants from Mexico to the U.S.: childhood predictors of adult physical and mental health.

OBJECTIVES: We tested whether positive selection on childhood predictors of adult mental and physical health contributed to health advantages of Mexican-born immigrants to the United States relative to U.S.-born Mexican Americans.

METHODS: We combined data from surveys conducted during 2000-2003 in Mexico and the U.S. with the same structured interview. We examined retrospective reports of childhood (i.e., < 16 years of age) predictors of adult health--education, height, childhood physical illness, childhood mental health, early substance use, and childhood adversities--as predictors of migration from Mexico to the U.S. at > or = 16 years of age. We estimated overall selection by comparing migrants to all non-migrants. We also examined selection at the family (members of families of migrants vs. members of families without a migrant) and individual (migrants vs. non-migrants within families of migrants) levels.

RESULTS: Distinguishing between family and individual selection revealed evidence of positive health selection that is obscured in the overall selection model. In particular, respondents in families with migrants were more likely to have > or = 12 years of education (odds ratio [OR] = 1.60) and be in the tallest height quartile (OR = 1.72) than respondents in families without migrants. At both the family and individual levels, migrants are disadvantaged on mental health profiles, including a higher prevalence of conduct problems, phobic fears, and early substance use.

CONCLUSIONS: Positive health selection may contribute to physical health advantages among Mexican immigrants in the U.S. relative to their U.S.-born descendants. Mental health advantages likely reflect a lower prevalence of psychiatric disorders in Mexico, rather than protective factors that distinguish migrants.