9,500 babies were born with a low birth weight in London last year. A little over half of them were premature but more than 4,000 were full term babies who weighed less than 2.5 kg or 5.5lbs.
Low birth weight is related to the rate of infant deaths and the risk of poor health for children. While the rate has come down in London over the past 10 years at 3.2% it is still above the average for England and in some areas it is markedly higher.
The rate in Tower Hamlets is 5%, the highest in London. It is also high in Newham, Harrow and Waltham Forest. Boroughs in South West London have much lower rates, particularly Richmond and Sutton.
The reasons for low birth weight in full term babies are complex. Smoking and drinking alcohol during pregnancy are factors but so too are medical problems for the mother such as conditions that affect the placenta and inhibit the baby’s growth.
Genetics also play a part. Some families are just smaller and low birth weight is far more common in Indian, Pakistani, Bangladeshi, Black African and Caribbean families than white Europeans. The areas of London with high rates all have a higher than average proportion of Black, Asian and minority ethnic residents.
But low birth weight has also been linked to social inequalities. It is more common in single mothers and for parents in manual occupations.
The government uses it as a public health indicator in relation to issues of premature mortality, avoidable illness, and inequalities in health, particularly in relation to child poverty.