Differential fertility indexes of 2106 healthy women and 211 patients with nodular goiter were investigated. Selection positive direction of nodular goiter is original cause of its prevalence in a population. Nodular goiter family aggregation in 69 patients with multinodular goiters patients and 79 patients with mononodular goiters were studied. Mononodular goiter is characterized by high nodular goiter familiar accumulation, than multinodular goiter. Mononodular goiters prevalence has increased during last 24 years. This phenomenon may be caused by nodular goiter selection positive direction.
