Asthma, Poor Respiratory Function in Children Linked More Firmly to Parents’ Lifestyles

She has her mother’s blue eyes and her father’s black hair. And if her mother was exposed to pollution during pregnancy, or if either parent smoked or was significantly stressed in her presence, she might also have poor lung function and/or respiratory disease later in life. Such are the findings of several independent initiatives.

Prenatal exposure to pollution is detrimental for children with asthma. The Fresno Asthmatic Children’s Environmental Study (FACES) is an ongoing research effort that examines the health effects of exposure to air pollutants in children with asthma. Recently, the investigators tracked backward to study how maternal exposure to pollutants (carbon monoxide, nitrogen dioxide, ozone, particulate matter) during pregnancy influences lung function status in asthmatic children as they age. ¹

For each mother, the team determined average exposure to pollutants per trimester as well as for the entire pregnancy. They then used spirometry to calculate lung function growth (forced vital capacity [FVC], forced expiratory volume in 1 second [FEV1], forced expiratory flow [FEF], peak expiratory flow [PEF]) for each of the mother’s children at ages between 6 and 15. The investigators repeated all pulmonary function tests several times, and adjusted the values for physical and socioeconomic variables.
   
Pulmonary function increased less in the asthmatic children born to mothers who were exposed to nitrogen dioxide during the first 2 trimesters of pregnancy. This was true for boys and girls, although the nature of pulmonary function “stunting” was different. For instance, boys exposed to nitrogen dioxide during the first 2 trimesters had reduced FVC. Girls exposed to this pollutant during the first trimester had low FEV1, while those exposed during the second trimester had reduced FEF. Exposure to particulate matter was linked with reduced FEV1 and FVC in girls, while boys who were exposed during the third trimester had low PEF and FEF.¹

This study is one of few that has examined the longer-term effects on children of prenatal exposure to pollution.

Parental stress and air pollution increase a child’s risk for asthma. The link between air pollution and asthma is well established, as is an association with low economic status. Researchers from the University of Southern California present a plausible link between the two associations. They report that parental stress might be the “last straw” that, when combined with the effects of exposure to pollutants, increases the child’s likelihood of developing asthma.²

The investigators followed 2,497 children who had no history of respiratory problems over a period of 3 years. They tracked several variables: development of asthma by first grade; parental stress (defined as the parent feeling as if life was overwhelming, unpredictable, or uncontrollable); parental educational levels; exposure to traffic-related pollution; and gestational exposure to tobacco smoke.

Data showed that children exposed to the combination of parental stress and pollution had a higher incidence of asthma than children exposed to only stress or only pollution.

Long-term respiratory problems in children are linked with exposure to tobacco smoke. Exposure to secondhand smoke is well known to be detrimental to respiratory function in children and adults. But researchers from the University of Arizona now report that the damage done by exposure to cigarette smoke during childhood persists into adulthood—regardless of whether the child exposed to second-hand smoking takes up smoking as an adolescent or adult.³ This relationship was strongest for cough and chronic cough. It was weaker, but nonetheless present, for wheezing and asthma that continued into adulthood.

The study conclusions were based on data generated by the Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD), a large, population-based study of 3,805 persons followed since 1972. Participants completed questionnaires every 2 years, and examiners looked for reports of parental smoking, active asthma, wheezing, coughing, and chronic coughing (persistent for 3 consecutive months). Overall, 52.3% of children in the study population were exposed to environmental smoke between birth and 15 years. This exposure was significantly associated with wheezing, coughing, and chronic coughing that persisted into adulthood.³