Asthma linked to low birth weight and early birth

Wednesday October 14th, 2009

There is a clear link between low birth weight and the chance of developing asthma, says new research.

Dr Catarina Almqvist Malmros and her team at the Karolinska Institutet in Stockholm, Sweden, looked at figures from 10,918 twins. The children and their parents filled in questionnaires at the ages of nine and 12. This information was linked back to their birth weight and how long into the pregnancy they were born.

Dr Malmros explains that because the twins were born at the same age and have the same genes, they are useful in research on the risk factors for disease.

She said: "Our study shows that there's a distinct correlation between foetal growth and asthma that's independent of gestational age and environmental or genetic factors."

The study appears in the journal Pediatrics. The team write that the number of children with asthma has risen steadily during the last decades, alongside an increase in low birth weight. It is possible that babies born too early may not have fully-developed lungs.

In this study, the overall rate of asthma was 14 per cent. Risk went up by 57 per cent for every 1,000 gram decrease in birth weight. It also went up by ten per cent for every week of prematurity.

They conclude that there is a link between growth in the womb and childhood asthma that is independent of gestational age, shared environment and genetic factors. This indicates that "foetal growth restriction affects lung development," they believe.

Ortqvist, A. K. et al. Familial factors do not confound the association between birth weight and childhood asthma. Pediatrics, Vol. 124, October 2009, pp. 737-43.

Tags: Allergies & Asthma | Child Health | Childbirth and Pregnancy | Europe | Genetics

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