THURSDAY, Oct. 7 (HealthDay News) -- A mother's negative emotions or behavior can worsen the severity of her child's asthma, new research suggests.

In the study, Japanese researchers followed 223 mothers for a year in order to assess how their stress levels, coping skills and parenting styles influenced asthma symptoms in their children, aged 2 to 12 years old.

Among children older than 7 years of age, a worsening of asthma was associated with mothers' excessive interference due to being overprotective. Among children younger than 7, more severe asthma symptoms were associated with mothers' chronic irritation and anger or a tendency to suppress expressions of emotion, the investigators found.

The study was published online Oct. 7 in the journal BioPsychoSocial Medicine.

"A mother's stress (or well-being) may be verbally or non-verbally conveyed to her child, and affect the child's asthmatic status via a psycho-physiological pathway, such as by immunoreactivity to allergens or a vulnerability to airway infections," Jun Nagano, of the Kyushu University Institute of Health Science in Fukuoka, Japan, explained in a news release from the journal's publisher.

"Our results suggest that the mothers of younger children may be advised not to worry about falling into 'unfavorable' parenting styles, but to pay more attention to the reduction of their own stress; and that the mothers of older children may be encouraged to increase their own well-being," Jun concluded.

More information

The American Lung Association has more about asthma and children.