Hydroxyvitamin D3 value of 25.56ng/ml at 26 weeks of pregnancy is slightly low. The normal value of hydroxyvitamin D3 is 20-100ng/ml, for women in pregnancy hydroxyvitamin D3 concentration over 30ng/ml is normal. Vitamin D deficiency in pregnant women is associated with an increased risk of osteomalacia, osteoporosis, preeclampsia, gestational diabetes mellitus, recurrent miscarriages, as well as an increased risk of fetal growth restriction, rickets, muscle weakness and subsequent chronic diseases. Vitamin D deficiency during pregnancy can be more sun exposure, in the spring, summer and fall between 10:00-15:00, the face and both upper arms directly exposed to the sun for 10-30 minutes, three times a week can achieve the purpose of preventing vitamin D deficiency. In addition, you can eat more vitamin D-rich foods in moderation, such as eggs, salmon, shrimp, oysters, mushrooms, etc., try not to supplement by yourself, it is recommended to go to the hospital to regulate the supplementation under the guidance of the doctor.