Month of birth and sensitization to dust mites in New England

Charts from 908 patients born in New England and seen at the Lahey Clinic because of allergic rhinitis or asthma or both were reviewed to ascertain whether or not a relationship existed between month of birth and subsequent development of allergy to house dust mites. Prick/puncture and intradermal skin tests for aeroallergens were performed on all patients. Skin tests for Dermatophagoides farinae (Df) mite were scored very positive (VP) in 451 patients (49.7%), mildly positive (MP) in 234 patients (25.7%), and negative (NEG) in 223 patients (24.6%). No discernible difference in frequency of birth could be identified for any single month for either Df-sensitive or Df-negative patients. Comparisons of 4-month periods (May through August, September through December, and January through April) failed to show a seasonal predilection for month of birth. During the 6-month period of February through July, a slight difference was observed for the overall group of 908 patients: 240 of the VP patients (53.2%), 111 of the MP patients (47.4%), and 105 of the NEG patients (47.1%) were born within this period compared with 211 VP patients (46.8%), 123 MP patients (52.6%), and 118 NEG patients (52.9%) who were born within the period of August through January. The difference among the groups was not statistically different (P = 0.20). Of the 225 children and adolescents who were either VP or MP, 125 patients (55.6%) were born within the period of February through July; of the 83 children and adolescents who were NEG, 37 patients (44.6%) were born within that same period. Although dust-mite allergic patients and, in particular, children and adolescents with asthma or rhinitis or both tended to be born within the period of February through July, no clear-cut statistically significant predilection in month of birth or season could be identified for New England-born adult or pediatric mite-allergic patients with rhinitis or asthma or both.