Why winter babies have a greater risk of asthma

WINTER babies are more at risk of developing asthma and other l ung- r el ated problems in later life, according to a Europe-wide study.

Those with birthdays in November, December and January face a greater likelihood of having weaker lungs as adults than those born in warmer months.

Other factors which can make lungs less efficient include respiratory infections as a child, having younger siblings and having an older mother or one who smokes.

However, the chances of having stronger lungs can be boosted by having a pet as a child and having older brothers and sisters, said researchers in Norway.

Cecilia Svanes of the Department of Global Public Health and Primary Care at the University of Bergen and her c ol l e agues analysed data on more than 12,000 people i n Britain and other countries.

Their report in the journal PLOS One found ‘a more rapid lung function decline was associated with season of birth’.

This was a ‘ novel finding’ and ‘ strong and consistent across European regions’.

Possible reasons include winter babies being exposed to viral infections or allergens while in the womb or suffering a higher rate of respiratory infections in their first few months of life.

Additional factors may include low vitamin D levels in the mother, which could i n turn raise the chances of ‘childhood wheeze and asthma’. Dr Svanes said: ‘It is logical that early life development also affects the systems that maintain our body and repair damage.

‘If so, then this could explain why some people do not tolerate exposure to certain toxins in later life. And that is actually what we f ound in t he course of our research.’

Dr Svanes added that it was possible that various stress factors, such as smoking or air pollution, could bring out or highlight any weakness.

She said: ‘Smoking is dangerous for everyone but these people are far more vulnerable. We can also imagine they would be particularly vulnerable to factors such as air pollution.’

Older mothers could be more likely to have children with poorer lung function because they are more likely to have emergency complications or Caesarean sections which can affect the growing child’s immune system.

Having younger siblings also made a person more likely to have poorer lung function in adulthood.

But some childhood influences had a positive effect on lung health. Children with older siblings were less likely to suffer lung decline, as were children who attended child daycare and had a childhood pet.

The study examined data on children aged nine to 11, followed up when they were 40 to 70.

It measured their lung function by testing how much air was exhaled in one breath.

‘Strong and consistent’