Objective To investigate alterations in serum NOV/CCN3 levels among women during mid-to-late pregnancy and elucidate its association with gestational diabetes mellitus （GDM） and pregnancy outcomes. Methods Based on the results of an oral glucose tolerance test （OGTT）， we categorized 252 pregnant women into two groups： the GDM group and the control group. Within the GDM group， participants were further stratified based on pre-pregnancy body mass index levels and pregnancy outcomes. We collected clinical data for all study subjects and compared differences in general information， biochemical indicators， as well as NOV/CCN3 levels between these groups. Results The serum levels of NOV/CCN3 in the GDM group were significantly higher compared to those in the control group （P < 0.001）. Spearman correlation analysis revealed a positive association between serum NOV/CCN3 and pre-pregnancy body weight， pre-pregnancy body mass index， insulin resistance index， and total cholesterol； while a negative correlation was observed with insulin sensitivity index （P < 0.05）. Logistic regression analysis demonstrated that NOV/CCN3 is an independent risk factor for the development of GDM ［OR = 1.097， 95% CI （1.020 ~ 1.179）， P = 0.013］， as well as adverse pregnancy outcomes in GDM patients ［OR = 1.032， 95% CI （1.020 ~ 1.045）， P < 0.001］. ROC analysis indicated AUCs of 0.840 and 0.784 for these associations respectively （P < 0.05）. Conclusions Serum levels of NOV/CCN3 in pregnant women at mid- to late-stage are associated with obesity， insulin resistance， and glucose-lipid metabolism， suggesting a potential role of NOV/CCN3 in glycolipid metabolism during gestational diabetes mellitus （GDM）. These findings provide novel insights for assessing the occurrence of GDM and predicting pregnancy outcomes in mid- to late-stage pregnancies.