Objective:To explore the serum 25-(OH)D levels of early pregnant women in Nanchong and their influencing fac-tors.Methods:1,098 pregnant women living in various regions of Nanchong were selected.The serum 25(OH)D values of early preg-nant women were detected by high performance liquid chromatography-tandem mass spectrometry.The present situation of vitamin D levels in pregnant women and their influencing factors were analyzed.Results:The serum 25-(OH)D level of pregnant women was 43.24±20.53 nmol/L in the early pregnancy.The deficiency rate was 67.85％.As individuals age,the levels of 25-(OH)D showed a gradual rise,peaking in the 35-year-old group.Compared with women without complications in the first trimester,the serum 25(OH)D level of early pregnant women after IVF-ET and with hypothyroidism or immune system diseases was higher(P＜0.05).The increase in body mass index(BMI)and the decrease in serum vitamin A concentration were risk factors for serum 25-(OH)D deficiency in early pregnancy(P＜0.05).Conclusion:The abnormal situation of vitamin among women in early pregnancy in Nanchong is the lack of ser-um 25(OH)D concentration.There are statistically significant differences in serum 25-(OH)D concentration in different ages,so indi-vidualized vitamin supplementation programs can be made for different pregnant women during prenatal examination.Maintaining the normal level of serum vitamin A concentration can reduce the risk of serum 25-(OH)D deficiency.