Exposure to second hand smoke is harmful for underweight babies, says a Dutch study.
Full-term babies with a low birth weight (5.5 pounds) have a significantly increased risk of developing respiratory symptoms such as coughing, wheezing and pulmonary infections up to age of five.
However, the risk is greater if these children are exposed to second hand smoke, reported health portal Health Central.
The association between birth weight and respiratory symptoms decreased after age five and was not significant by age seven, the researchers found.
Analyzing data on more than 3,600 babies, the researchers found that during the first seven years of life, almost 39 percent of them had at least one wheezing episode, close to 52 percent had cough at night and more than 37 percent had a lower respiratory infection.