MONDAY, March 21 (HealthDay News) -- A woman's use of birth control pills before pregnancy does not increase the risk of respiratory problems in her children, according to a new study.

Some studies have suggested that a mother's use of birth control pills may increase the risk of asthma in children, but the data is limited and inconclusive, said the authors of the new study.

The researchers examined the link between the type of birth control pill used by Norwegian mothers before pregnancy and lower respiratory tract infections in 60,225 children followed until the age of 6 months, lower respiratory tract infections and wheezing in 42,520 children followed to 18 months old, and asthma in 24,472 children followed until age 3.

The investigators found no association between the use of estrogen-progestin combined pills prior to pregnancy and lower respiratory tract infections, wheezing or asthma in children. There was a small association between the use of progestin-only pills in the year before pregnancy and wheezing in children at 6 to 8 months, although this type of pill was not commonly used, the study authors noted.

The study was scheduled for presentation Monday at the annual meeting of the American Academy of Allergy, Asthma & Immunology (AAAAI), held in San Francisco.

"We found that use of the combined pill, taken by most women who use [oral contraceptive pills], was not associated with adverse respiratory outcomes in the offspring. This should provide reassurance to the vast majority of women using [oral contraceptives] during their childbearing years," senior author Dr. Stephanie J. London, principal investigator at the U.S. National Institute of Environmental Health Sciences, said in an AAAAI news release.

"The small association with the much less commonly used progestin-only pill may not reflect cause and effect but does suggest that researchers look at these two types of pills separately in the future," she added.

Because this study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.

More information

The American Lung Association has more about asthma and children.