While drinking milk during pregnancy can protect babies against developing asthma, eating low-fat yogurt has been shown to have the opposite impact altogether, increasing the risk of babies developing both asthma and hay fever, new research suggests.

The subtle differences were observed in a study carried out by researchers at the Harvard School of Public Health. More details and findings will be presented at the European Respiratory Society's Annual Congress in Amsterdam on September 25.

While assessing the prevalence of asthma and hay fever from the registries of the Danish National Birth Cohort, researchers found that women who ate low-fat yogurt with fruit once a day were nearly twice as likely to birth children who developed asthma by the age of seven, compared to the children of women who didn't consume low-fat yogurt.

The same children were also more likely to have hay fever.

While non-fat-related nutrients in the yogurt may increase the risk, researchers are also studying the possibility that low-fat yogurt may serve as a marker for other dietary and lifestyle factors.

Another study published last month found that infants who live in moldy homes are three times more likely to develop asthma by the age of seven. Common symptoms of asthma include coughing, especially at night, wheezing or a whistling sound, trouble breathing and frequent chest colds.