男性乳房发育症在新生儿中的发生率为60-90%,通常在几周内消退。[3]McKiernan JF, Hull D. Breast development in the newborn. Arch Dis Child. 1981;56:525-529.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1627340/pdf/archdisch00767-0041.pdfhttp://www.ncbi.nlm.nih.gov/pubmed/7271286?tool=bestpractice.com大多数的青春期男性会发生男性乳房发育,一般从年龄11-12岁开始。到14岁时,60%的青春期男性会出现男性乳房发育。[4]Nydick M, Bustos J, Dale JH Jr, et al. Gynecomastia in adolescent boys. JAMA. 1961;178:449-454.http://www.ncbi.nlm.nih.gov/pubmed/14480779?tool=bestpractice.com多数患者在几个月内恢复正常。到19岁,男性乳房发育症的患病率为5-15%。在25-45岁的正常男性中,男性乳房发育症的发生率为33-41%,在超过50岁的男性中,其发生率为55-60%。[5]Nuttall FQ. Gynecomastia as a physical finding in normal men. J Clin Endocrinol Metab. 1979;48:338-340.http://www.ncbi.nlm.nih.gov/pubmed/429488?tool=bestpractice.com[6]Niewoehner CB, Nuttall FQ. Gynecomastia in a hospitalized male population. Am J Med. 1984;77:633-637.http://www.ncbi.nlm.nih.gov/pubmed/6486139?tool=bestpractice.com大多数男性乳房发育症是无症状的,并且患者不知道自己有乳房组织。男性乳房发育与肥胖密切相关。[6]Niewoehner CB, Nuttall FQ. Gynecomastia in a hospitalized male population. Am J Med. 1984;77:633-637.http://www.ncbi.nlm.nih.gov/pubmed/6486139?tool=bestpractice.com有研究随机选择了男性住院患者,在BMI小于19kg/m^2的患者中,男性乳房发育症的发生率≤12%,但是在BMI大于25kg/m^2的患者中,男性乳房发育症的发生率超过80%。尸检结果提示,男性乳房发育症在男性中的发生率约为45-50%。[7]Anderson JA, Gram JB. Male breast at autopsy. Acta Pathol Microbiol Immunol Scand. 1982;90:191-197.http://www.ncbi.nlm.nih.gov/pubmed/6285667?tool=bestpractice.com