• birth weight
• risk factors

“How much did he/she weigh?” is often the first question proud parents are asked after they have announced the sex of their newly delivered progeny. A big baby, according to common knowledge, is a healthy baby. What evidence lies behind this popular assumption?

Paediatricians have long been familiar with the increased risk of mortality and early morbidity of babies born very small or very early. These babies have a greater risk of dying throughout the first year of life.¹ In addition, they are more likely to have a range of morbidities, particularly neurological, respiratory, and gastrointestinal.^2,3

In the last 20 years or so, there has been increasing evidence that size at birth is also associated with later health, particularly with the chronic degenerative diseases that are major causes of death in middle and later life. The best documented are the relations between smaller size at birth and higher death rates from coronary heart disease and stroke.^4–7 Smaller size at birth is also related to increased levels of cardiovascular risk factors such as hypertension,⁸ type II diabetes mellitus,⁹ and hyperlipidaemia.¹⁰ However, high birth weight is also associated with long term health. People with high birth weight have higher death rates from prostate cancer¹¹ and possibly breast cancer.¹² …