Is month of birth a risk factor for subsequent development of pollen allergy in adults?

A comparison of the date of birth of 1501 adult patients with severe season al respiratory allergy (allergic rhinitis or bronchial asthma) due to parie taria, olive, and grass pollens with the expected births within 2,020,420 b irths in South Greece during the same period, was performed. The relative r isk for developing respiratory allergy was characteristically increased in those born in a specific period of time different for each pollen. The rela tive risk for parietaria was increased (1.47) in those born in March; Sor o live it was 1.6 for May; 1.2 for April; and 1.4 for March, while the relati ve risk for grasses was 1.2 in those born in June and July. These findings are indicative of the importance of the month of birth; that is, the entry exposure to pollens, for the development of respiratory allergy to certain pollens during adulthood. Because our findings do not directly correlate co mpletely with the aerobiology studies on pollen calculation in Athens' atmo sphere, we supposed that other environmental factors, e.g., the local inten sity the first pollination or the influence of weather conditions, may cont ribute to the final development of respiratory allergy as well. The most im pressive finding was the significant influence of the month of birth ill th e development of respiratory allergy dire to parietaria and olive pollens d uring adulthood.