(RxWiki News) Some babies may be more likely than others to develop respiratory infections. This is especially true of babies prone to allergies. Secondhand smoke can make the situation worse.
A recent study found that babies prone to allergies spent more time in the hospital with respiratory infections if they were exposed to secondhand smoke.
Secondhand smoke was already known to be a risk factor for respiratory infections in babies.
The Centers for Disease Control and Prevention states that secondhand smoke contains more than 7,000 chemicals, including 70 that can cause cancer.
"Don't smoke around babies."
The study, led by Meghan Lemke, MD, of the Department of Pediatrics at Vanderbilt University School of Medicine in Tennessee, aimed to see whether being exposed to secondhand smoke made respiratory infections worse for babies.
The researchers focused on children with atopy or who had a family history of atopic syndrome. Atopy or atopic syndrome means a person is very prone to allergies.
A person with atopy or atopic syndrome very easily develops eczema, hay fever, allergic asthma and similar allergy conditions, including food allergies.
The 451 children included in the study were under age 1 and all had lower respiratory tract infections and visited an ER, an outpatient clinic or were hospitalized. None of the babies had been premature or born underweight.
Just over half the babies (57 percent) had been exposed to secondhand smoke.
Just over a third (36 percent) had a mother who had atopic disease. About two-thirds (68 percent) of the babies had a family history of atopy.
The researchers measured how severe the respiratory infections for the babies were in two ways. They looked at how long the babies remained in the hospital, and they used an assessment called the bronchiolitis severity score.
The researchers did not find that babies' infections were any more or less severe based on whether their mothers had atopic disease.
Babies who had a family history of atopy and were exposed to secondhand smoke tended to have a longer stay in the hospital than babies with the family history but not exposure to secondhand smoke.
In their analysis, the researchers found that babies with a family history of atopy spent 23 percent longer in the hospital if they had been exposed to secondhand smoke than if they hadn't.
The bronchiolitis severity score was not different among the babies, regardless of whether they were exposed to secondhand smoke or not.
The researchers noted that secondhand smoke is already a risk factor that can contribute to how severe a baby's lower respiratory tract infections can be.
This study found that those babies also spent longer periods of time in the hospital with their infections if they have been exposed to secondhand smoke.
The study was published June 4 in the journal Annals of Allergy, Asthma & Immunology.
The research was published by a Thrasher Research Fund Clinical Research Grant and by the National Institutes of Health. The authors declared no conflicts of interest.