McEniry, Mary, and Alberto Palloni
Working paper no. 2008-03
Background: Season of birth has been shown to be a useful proxy of early growth and development among adults. It is an indicator that disentangles the effects of childhood conditions (health, SES) on adult health and sheds light on the adult health effects of poor nutrition and infectious diseases in utero.
Methods: We used a sample of 1438 Puerto Ricans 60-74 years of age born in Puerto Rico who lived in the countryside during most of childhood. Retrospective measures of early childhood (health status, SES); knee height, height and weight measurements and adult risk factors (adult SES, obesity, self-reported smoking, exercise, diabetes) were obtained through home interviews. We defined exposure period to poor nutrition and infectious and parasitic diseases to be the third-fourth quarter. Using Cox and log logistic hazard models we examined the degree to which overlap between late gestation (last trimester of pregnancy) and exposure period had important effects on the timing of onset of and the probability of ever experiencing adult heart disease while controlling for other risk factors.
Results: Risk of onset of heart disease was 65% higher among those born when the third trimester of gestation overlapped completely with exposure period compared with unexposed individuals but there were no differences in median time of onset by exposure for those reporting heart disease.
Conclusions: Effects of exposure to a high risk period operate through the probability of ever experiencing heart disease not through the timing of onset among those who do experience it.