Age at menarche at sea level and high altitude in Peruvian women of different ethnic background.

The objective of the present study was to determine recalled age at menarche in women of Quechua and non-Quechua ancestry living in the cities of Lima (altitude 150 m), Cusco (altitude 3,400 m), and Cerro de Pasco (altitude 4,340 m), Perú. The sample included 296 Mestizo urban women, 20-30 years, who were natives of Lima (n = 72), Cusco (n = 81), and Cerro de Pasco (n = 143). Ethnic composition was determined by two parental surnames, and women were classified as Quechua when one or both surnames were of Quechua origin and non-Quechua when both surnames were of Spanish origin. Age at menarche was obtained by recall to nearest year. In Quechua as in non-Quechua women, age at menarche occurred later as residence altitude increased. Mean ages at menarche for the combined Quechua and non-Quechua samples were 13.1 ± 1.4 years in Lima, 13.9 ± 1.9 years in Cusco, and 14.6 ± 1.69 years in Cerro de Pasco. Thus age at menarche occurs later at high altitude independent of ethnic influence. © 1994 Wiley-Liss, Inc.