Obesity and Pregnancy—The Propagation of a Viscous Cycle?

Abstract

“Obesity is a chronic disease, prevalent in both developed and developing countries, and affecting children as well as adults. Indeed, it is now so common that it is replacing the more traditional public health concerns, including undernutrition and infectious disease as one of the most significant contributors to ill health” (1). In the United States, the adult age-adjusted prevalence of obesity [body mass index (BMI) ≥ 30] was 30.5% in 2000, compared to 22.9% from 1998–1994. The prevalence of overweight (BMI ≥ 25%) increased from 55.9–64.5% during the same period of time (2). Potentially more important is that the prevalence of obesity in adolescents has also increased, particularly among Hispanic and African-American populations. In the United States, the prevalence of obesity, defined as weight greater than the 95th percentile of the sex-specific BMI for age, was 15.3% among 6–11 yr olds, an 11.3% increase since 1988–94 (3). In the last decade, there has been a plethora of data relating to the fact that adipose cells are not just a storage depot for excess calories, but rather a metabolically active tissue. Leptin and, more recently, a number of additional cytokines have been reported to have paracrine as well as endocrine effects on a variety of target tissues. Relative to the issue of cytokines and insulin resistance, TNF-α has been reported to modify the insulin signaling pathway via serine phosphorylation of insulin receptor substrate-1, one primary substrate of insulin receptor (4). How then do these data relate to pregnancy and the increased prevalence of obesity in the past decade?