One criticism of the fetal programming literature is the potential for confounding by socioeconomic status (SES). Low SES is an established risk factor for CVD, NIDDM, and the IRS. Infants of low SES parents may tend to have lower birth weights and may have low SES as adults. We note, however, that in some study populations, such as the Harvard Nurses study, heavier infants tended to be from lower SES groups.