Women suffering from asthma are more prone to develop preeclampsia -- a dangerous pregnancy complication characterised by high blood pressure - and run a higher risk of giving birth to underweight babies, says a new study.

Asthma is a common disease caused by chronic inflammation in the lungs with symptoms of coughing and breathlessness.The study, published in the Journal of Allergy and Clinical Immunology: In Practice, suggests that well-controlled asthma during pregnancy could reduce the relative incidence of complications during pregnancy and childbirth."We found that the risk of preeclampsia is 17 per cent higher in women with asthma compared to women without asthma," said the study's lead author Gustaf Rejno from Karolinska Institutet in Sweden.

The researchers used data from the Swedish birth registers and examined the link between asthma in pregnant women and the relative pregnancy and delivery outcomes. After studying more than one million births to just over 700,000 women between 2001 and 2013, it was found that 10 per cent of the babies born had a mother suffering from asthma. In addition, women with asthma were more likely to have underweight babies, instrumental deliveries, caesarean sections and shorter pregnancies.

In order to ascertain whether the complications could be attributed to hereditary or environmental factors, the researchers also identified the women's asthma-free cousins and sisters who had given birth during the same period. On comparing the groups they found that the correlations between maternal asthma and complications during pregnancy and delivery held."It seems to be the asthma per se that causes these complications," Rejno said.