Socioeconomic determinants of intrauterine growth retardation.

This paper reviews the evidence bearing on socioeconomic determinants of intrauterine growth retardation (IUGR). The primary focus is on those factors with a quantitatively important impact from a public health perspective, as indicated by their large etiologic fraction (population attributable risk). In developed countries in which a sizeable proportion of women smoke during pregnancy, cigarette smoking is associated with the largest etiologic fraction (by far), followed by low gestational weight gain (primarily due to low energy intake) and low prepregnancy body mass index (BMI). In developing countries where undernutrition is prevalent and pregnant women do not smoke, low maternal weight gain and BMI assume even greater importance, as does short maternal stature. A major section of the paper concerns the large within-country socioeconomic disparities in IUGR and the possible mechanisms underlying these disparities. In developed countries, differences in cigarette smoking explain a large part of the disparity; low weight gain and short stature may also be important mediators in some settings. Future etiologic studies should assess a wide scope of potential determinants and will require large sample sizes to control for their mutually confounding effects.