London, Sep 5 (IANS): A smaller foetal size during the first and second trimesters of pregnancy can signficantly increase the risk of asthma and reduce the lung function in children, a study has found.

Previous studies found that the reduced foetal size during the first and second trimesters of a pregnancy increased the risk for asthma in children up to the age of ten years.

In the new study, the authors tested the hypothesis that reduced foetal size would be associated with reduced lung function and persistent asthma from ages 5 to 15 years.

Antenatal factors in the pregnant mother contributes to the life-long respiratory well-being of the child, the researchers said.

"First trimester foetal size -- a surrogate for foetal lung size -- is relevant to symptoms and respiratory physiology through to 15 years of age. These findings suggest that antenatal factors contribute to life-long respiratory well-being." said Stephen Turner from University of Aberdeen in Britain.

On the other hand, the study revealed that larger foetuses were at reduced risk for asthma and also had better lung function.

"Ultimately, any intervention is going to boil down to mothers not smoking or drinking, having a balanced diet and taking regular exercise - but this is good incentive for a healthy maternal lifestyle" Turner suggested.

For the study, a total of 2,000 mothers were recruited from the antenatal clinic in Aberdeen between 1997 and 1999.

Foetal size in the first and second trimester was ascertained by routine ultrasound scan. Asthma status and lung function were determined at ages 5, 10 and 15 years.

In the study, foetal size was expressed as a z score, which is a statistical method of expressing difference from normal, with four z scores covering the range from abnormally small to abnormally large.

An increase of each z score in the first trimester size was associated with an overall 22 per cent reduced risk for asthma between ages 5, 10 and 15 (OR 0.78).

The increase in foetal size was also associated with an increased lung function, the researchers concluded.

The findings were presented at 2016 European Respiratory Society (ERS) International Congress in London, recently.