The vast majority of women 415 (98.8%) had serum 25(OH)D < 20 ng/ml (50 nmol/l) with an additional
4 women (30 ng/ml or 75 nmol/l). 25(OH)D concentrations were positively and independently associated
with educational status and use of vitamin D supplements, but not with other demographic, lifestyle,
reproductive, or anthropometric factors. 25(OH)D levels were not associated with dietary factors in this
population, as there is little access to foods containing vitamin D in Mongolia. No production of previtamin
D3 was observed until March and was maximally effective in April and was sustained through
July