The influence of a family history of asthma and parental smoking on airway responsiveness in early infancy

N Engl J Med. 1991 Apr 25;324(17):1168-73. doi: 10.1056/NEJM199104253241704.


Background: Airway responsiveness to inhaled nonspecific bronchoconstrictive agents has been demonstrated in normal, healthy infants. However, it is unknown whether airway responsiveness is present from birth or if it develops as a result of subsequent insults to the respiratory tract. To investigate this question, we assessed airway responsiveness in 63 normal infants at a mean age of 4 1/2 weeks.

Methods: Respiratory function was measured with use of the partial forced expiratory flow-volume technique to determine the maximal flow at functional residual capacity (VmaxFRC). The infants inhaled nebulized histamine at sequentially doubled concentrations (0.125 to 8.0 g per liter), until a concentration was reached at which the VmaxFRC fell by 40 percent from the base-line value (PC40) or until a concentration of 8.0 g per liter was reached. We also assessed maternal serum levels of IgE, cord-serum levels of IgE, the infants' skin reactivity to several allergens, and the parents' responsiveness to histamine and obtained family histories of asthma and smoking.

Results: Airway responsiveness was increased in infants with a family history of asthma (n = 19; median PC40, 0.78 g per liter; 95 percent confidence interval, 0.44 to 1.15; P less than 0.01), parental smoking (n = 13; median PC40, 0.52 g per liter; 95 percent confidence interval, 0.43 to 5.40; P less than 0.05), or both (n = 20; median PC40, 0.69 g per liter; 95 percent confidence interval, 0.37 to 2.10; P less than 0.05), as compared with the infants with no family history of asthma or smoking. The infants with no family history of asthma or smoking had a median PC40 of 2.75 g per liter (95 percent confidence interval, 1.48 to 4.00). No significant relations were detected between the immunologic variables and the PC40 in the infants.

Conclusions: This study indicates that airway responsiveness can be present early in life and suggests that a family history of asthma or parental smoking contributes to elevated levels of airway responsiveness at an early age.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Asthma / genetics*
  • Bronchial Provocation Tests
  • Bronchoconstriction / drug effects
  • Bronchoconstriction / physiology*
  • Female
  • Fetus / drug effects
  • Forced Expiratory Flow Rates
  • Forced Expiratory Volume
  • Histamine
  • Humans
  • Immunoglobulin E / analysis
  • Infant
  • Male
  • Parents*
  • Pregnancy
  • Skin Tests
  • Smoking*


  • Immunoglobulin E
  • Histamine