113 Tibetan. females in Xiahe County (Gansu P rov ince ) and 400 females of Hart na t iona l i ty in Gansu were subjected to clinical pe lv ic measurement and Thorns, X r a y pe lv ime t ry . Each female had h i s tory of spontaneous ful l term delivery. Xiahe County is a district in the southwest of Gansu , about 267 miles a w a y from Lanzhou and 2900-3023 metres above sea level w i th a colder climate. I t is a plateau of pasture land. More than 80 % ef the populat ion in this area are Tibetan, s, most of whom are herdsmen. Tibetan women do much heavy physical work. T h e y have to car ry a large water bucket on. thei r back a~.d have to work in stooping posi t ion in. the fields.