Infant Weight Gain and Obesity Risk

Understanding Obesity’s Developmental Origins

Obesity, once thought to be little more than an unfortunate failure of will and self-restraint, has much deeper and more complex roots. Genes clearly play a role in driving an individual’s propensity to gain excess weight, as does the environment and gene environment interactions. Early-life influences, beginning with the intrauterine environment and continuing through the first few years of life, also shape the trajectory of weight gain and body fatness throughout the life course.

Later data showing that higher birth weight is also associated with obesity, diabetes, and other adult diseases has helped extend this concept into the “developmental origins hypothesis,” which encompasses the preconception period as well as many critical periods of fetal and infant development. During each of these periods, several factors appear to have a substantial impact on obesity in childhood and adulthood. This article briefly outlines some of the key prenatal and early life influences on the development of adult weight and obesity.In the 1980s, intriguing research from British epidemiologist David Barker and colleagues sparked a flutter of research into what was then called the “fetal origins hypothesis” of chronic disease. (1) They proposed that coronary heart disease, type 2 diabetes, stroke, hypertension, and other chronic diseases develop in part due to undernutrition during fetal life and infancy. (2)

Prenatal Influences on Obesity

The warm, nutrient- and hormone-rich environment of the uterus has a profound effect on fetal development. Brief or fluctuating changes in the intrauterine environment at critical or sensitive periods of the developmental process, as well as longer term alterations, could have irreversible, lifelong consequences. Three modifiable prenatal factors that appear to shape fetal nutrition and health in later life are

• the mother's smoking habits during pregnancy;
• the mother's weight gain during pregnancy; and
• the mother's blood sugar levels during pregnancy, specifically, whether she develops pregnancy-related (gestational) diabetes.

It makes intuitive sense that the mother's diet during pregnancy should also affect fetal development and birth weight, but evidence for this is inconsistent.