Low birth weight is not associated with thyroid autoimmunity: a population-based twin study.

Context: Low birth weight has been proposed as a risk factor for the development of antibodies toward thyroid peroxidase (TPOAb) and thyroglobulin (TgAb) in adult life. However, the association could also be due to genetic or environmental factors affecting both birth weight and the development of thyroid autoantibodies. The effect of these confounders can be minimized through investigation of twin pairs.