Increased risk of wheeze and asthma in young children whose mothers smoke during the pregnancy

Wheeze associated with prenatal tobacco smoke exposure: a prospective, longitudinal study 2000; 83: 307-12

Young children may be at increased risk of wheeze and asthma if their mothers smoke during pregnancy, finds research in the Archives of Disease in Childhood. This held true irrespective of the effects of exposure to environmental tobacco smoke.

Over 8500 mothers were surveyed about their smoking habits during pregnancy and the respiratory health of their children, as part of the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC). Around one in five children were wheezy between the ages of 18 and 30 months, the risk being higher if the mother smoked while pregnant. This is an important period for determining levels of risk, say the authors, because earlier on in a child's life, wheeze could be caused by infections.

Environmental tobacco smoke (ETS) and smoking during pregnancy seemed to confer similar levels of risk for wheeze in infancy and early childhood. But while the amount of exposure to ETS increased the corresponding risk of asthma or wheeze, light smoking during pregnancy conferred the same level of risk as heavier smoking. Applied across the population, smoking during pregnancy and ETS are likely to account for around 1.5 per cent of wheeziness in all young children, say the authors.

Four out of 10 children were wheezy at some point throughout the 30 months of monitoring, attributable to other identifiable risk factors, such as a family history of asthma, premature delivery, male sex of the child, and living in rented accommodation.

Contacts:

Dr Andrew Lux, Bath Unit for Research in Paediatrics, Royal United Children's Hospital, Bath. Andrew.Lux@ruh.bath.swest.nhs.uk

Pam Holmes, Avon Longitudinal Study of Parents and Children (ALSPAC/Children of the Nineties)