Environmental temperature during gestation and body mass index in adolescence: new etiologic clues?

Abstract

Being born during certain parts of the year is linked to the presence of obesity in later years. Animal studies suggest that environmental temperature during fetal development may be one aspect of the link to later weight status, but this relationship has not been extensively studied in humans. The present study investigates whether environmental temperature during different stages of human gestation is associated with body mass index (BMI) during late adolescence. Questionnaire data were collected from adolescents (n=578; ages 15-19 y) attending public schools in a mid-Atlantic US city. Pearson correlations were used to assess association of BMI with mean environmental temperature (from meteorological records) during trimesters of intrauterine development and at birth. BMI was significantly correlated with environmental temperatures in the second and third trimester, but only among female African Americans. Among females, those 'at risk for overweight' or overweight (BMI >85th percentile) tended to be born during periods of warmer average environmental temperatures (>13.2 degrees C). However, this effect was reliable only among African American females (relative risk=2.51, CI 1.07-5.91). A similar, non-significant tendency emerged among Caucasian females, but there was no such effect in males. Environmental temperatures during pregnancy and at birth are associated with the likelihood that African American females become overweight as adolescents. Possible biological and dietary mechanisms for this finding are discussed.