From Sadie Williams
The evolutionary explanation for the preponderance of high-birthweight babies in the poorest countries is spurious (8 May, p 17). There is a much simpler explanation. It is well known that infant mortality is much higher for babies with low birthweight. In the poorest countries, low-birthweight babies will be less likely to come to full term and survive the birth. Any study based on live births is therefore likely to show a preponderance of heavier babies in the poorest areas.
Henley-on-Thames, Oxfordshire, UK
