Objective:To investigate the effect of serum 25 hydroxyvitamin D (25OHD) levels in early pregnancy on glucose and lipid metabolism indicators and pregnancy outcomes in women with polycystic ovary syndrome (PCOS).Methods:A prospective study was conducted on 132 pregnant women with PCOS admitted to the Yanda Hospital in Hebei from January 2021 to June 2022. They were divided into four groups based on serum 25OHD levels: severe vitamin D deficiency group (12 cases with 25OHD<10 ng/ml), vitamin D deficiency group (28 cases with 25OHD: 10-<20 ng/ml), vitamin D deficiency group (55 cases with 25OHD: 20-<30 ng/ml), and vitamin D sufficient group (37 cases with 25OHD≥30 ng/ml). Four groups of serum glucose and lipid metabolism indicators [total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), fasting blood glucose (FPG), fasting insulin (FINS), insulin resistance index (HOMA-IR)] and poor pregnancy outcomes were compared.Results:As the degree of vitamin D deficiency worsens in early pregnancy, serum levels of TC, TG, LDL-C, FPG, FINS, and HOMA-IR gradually increased (all P<0.05), while serum levels of HDL-C gradually decreased (all P<0.05). The serum 25OHD level in early pregnancy of PCOS pregnant women was negatively correlated with serum TG, FINS levels, and HOMA-IR levels ( r=-0.523, -0.612, -0.354, all P<0.05), and positively correlated with serum HDL-C levels ( r=0.484, P<0.05). There was no significant correlation with serum TC, LDL-C, and FPG levels (all P>0.05). The incidence of adverse pregnancy outcomes in the vitamin D sufficient group was significantly lower than the other three groups [8.11%(3/37) vs 34.55%(19/55), 46.43%(13/28), 8/12, P<0.05], while the incidence of adverse pregnancy outcomes in the vitamin D insufficient group was significantly lower than that in the vitamin D severely deficient group (34.55% vs 8/12, P<0.05). Conclusions:With the decrease of serum 25OHD levels in early pregnancy, the disorder of glucose and lipid metabolism in PCOS pregnant women gradually worsens, and the incidence of adverse pregnancy outcomes gradually increases.