Österbrand M, et al. - This is the first prospective population-based study examining the prevalence of premature thelarche (PT) in 18-month-old girls and the incidence of clinically assessed PT for girls aged 18–36 months. The study sample consisted of 3,140 girls born at Northern Älvsborg county hospital (NÄL) in Trollhättan, Sweden. For clinical outcome and 17β-estradiol, all girls with PT have been involved and followed. Data reported that the prevalence of PT at 18 months was 1.6/1,000. Finding revealed that clinically evaluated PT incidence was 1.1/1,000. The result is consistent with other studies reporting medical records incidence of PT (0.4–40/1,000). As in the other studies, the outcome of PT in the study is that the vast majority of girls only show benign symptoms.