Problem: A high percentage of women schoolteachers having fertility problems were observed by three independent teams.
Method: Expected percentage of educators was calculated in 4650 sub-fertile women and 2,062,891 women at reproductive age. To explore the possibility that schoolteachers' contact with childhood viral infections results in alterations of peripheral blood natural killer (NK) cells, a multiple linear regression analysis for profession, age, difficulty to conceive, number of abortions/implantation failures (predictor variables) was performed in childless educators (210) and housewives (184).