Effect of Environmental Manipulation in Pregnancy and Early Life on Respiratory Symptoms and Atopy During First Year of Life: A Randomised Trial

Abstract

Because sensitization to indoor allergens is a major risk factor for asthma, reducing exposure to such allergens might be a realistic approach to primary prevention. A strict regimen of environmental manipulation has beenwell accepted and has maintained low allergen levels during pregnancy and through the first year of life. Its effect on symptoms in the first 12 months now has been studied prospectively in 291 high-risk couples in which both parents were atopic (skin-test positive), the mother was sensitized to indoor allergens, and there was no cat or dog at home. Participants were randomly assigned to receive environmental manipulation or no intervention. The study also included 161 high-risk infants living with pets and 168 low-risk infants whose parents were nonatopic. Study couples received a customized cot and mattresses made with allergen-proof material. They were asked to wash their infant's bed linen in hot water (55°C) once a week. Carpets and soft furnishings were treated with benzyl benzoate. Respiratory symptoms were consistently less likely to develop in the first year of life in children in the environmental manipulation group than in children in the control group. Differences were most evident for severe wheezing episodes with shortness of breath, the use of prescription drugs for attacks of wheezing, and the occurrence of wheezing after vigorous play, exertion, or crying. The risk of all respiratory symptoms was similar in control infants and high-risk infants with pets. Low-risk infants had significantly fewer respiratory symptoms than control infants. Very few infants developed a positive skin reaction to inhalant allergens, but this was by far more frequent in the high-risk children with pets. These preliminary findings suggest that strict environmental controls are able to limit respiratory symptoms in young infants at high risk for allergic disease. Further work will be needed to learn whether living in a low-allergen setting reduces allergy and asthma later in life.