Children's growth rate linked to birth order, study claims

THE GUARDIAN , LONDON

Fri, Sep 14, 2007 - Page 6

Children with older brothers and sisters are at risk of impaired growth in early life, a study of thousands of British families has found, while those with several older brothers are most affected.

Medical records show that by the age of 10, such children are already significantly shorter than the average. Those born last appear to grow up in an environment where parents are more stretched for time, money and the ability to lavish attention.

David Lawson, an anthropologist, working at University College London, found that when other socioeconomic factors were taken into account, children's height was strongly dependent on the number of their older siblings.

Scientists had followed children born to nearly 14,000 families in the 1990s. Every year, the children's height and general development was recorded.

In a family of four children, the siblings were 2.5cm shorter than average.The youngest child was most affected. The study found that while having older siblings of either sex affected a younger child's development, the effect of older sisters was more mild. One explanation put was that boys are more demanding, and stretch the resources of parents more so than daughters.

The height of children with younger siblings was also slightly less than average, but the effect was temporary, with children being normal height by age 10.

Lawson urged caution in interpreting the results, which have not yet been published. But if the findings are confirmed, they will add to a growing body of work that suggests younger siblings fare less well in life, often because they have poorer nutrition and do not perform so well at school.

Research by the World Bank in 2001 found that better nourished children performed significantly better at school, partly because they entered school at an earlier age, but, more significantly, because they were more productive in class.

On Wednesday, Lawson told the British Association festival of science in York, England: "All else being equal, growth is significantly retarded by the presence of siblings. Older siblings are associated with relatively higher costs than younger siblings, and in most cases, brothers represent a larger threat to development than sisters."