This study examined the situation of maternal micronutrient supplementation before and during pregnancy in Northwest China and the rates of and factors related to the adherence to micronutrient supplementation among pregnant women in this region, where dietary micronutrient intake is commonly insufficient. Results showed that in total, 83.9% of women took at least one kind of micronutrient supplement before or during pregnancy. Folic acid and calcium were the primarily used micronutrient supplements; few participants used multiple micronutrient supplements (MMS) or iron. Adherence to supplementation of all micronutrients was low and well below standards recommended by the Chinese guidelines or WHO. Higher educational levels, higher income levels, urban residence, and better antenatal care (including pregnancy consultation and a higher frequency of antenatal visits) were associated with high adherence to micronutrient supplementation.