SEVERE asthma attacks in pregnancy can harm mothers and babies, a study has warned.
It found sufferers were 30 per cent more likely to develop potentially deadly pre-eclampsia.
And newborns were more likely to be underweight or have an abnormality, said the Canadian review of 100,000 pregnancies over nine years.
Babies were also 20 per cent more likely to develop asthma themselves and had a higher chance of catching pneumonia by the age of five.
But many mums-to-be choose to reduce their asthma treatment because they think it may harm their child.
Senior researcher Dr Teresa To said: “This is the biggest study looking at the risks associated with severe asthma symptoms in pregnancy and it’s also the first to show the longer-term impacts on children up to the age of five years.
“Our results reinforce the findings of smaller studies that uncontrolled asthma can be bad for mothers and their babies.”
She added: “Nearly 40 per cent of pregnant women decrease or stop taking asthma medication because they are worried that it could be harmful to their unborn babies.
“However, our study indicates that severe asthma symptoms present the greater risk to mother and baby.”