Washington, Aug 26 - Women with large waistlines are more likely to develop asthma even if they have a normal body weight, a new study suggests.

Obesity is a risk factor for adult asthma, especially in women, but few studies have looked at the relationship between abdominal obesity (large waist size) and asthma.

Researchers led by the Northern California Cancer Centre's Berkeley team of scientists used data from the California Teachers Study which began in 1995.

The study involved 133,479 female teachers and school administrators either employed in the California public school system or retired and receiving retirement benefits. Women participants answered questionnaires in 1995, 1997, 2000 and 2005.

The researchers analysed 88,304 women and found that 11,500 (13 percent) of them were obese in 1995, including 1,334 who were extremely obese.