Although the results did not support that study country (P for subgroup difference ═ 0.83, Figure 5A), maternal age (P for subgroup difference ═ 0.29, Figure 5B), the timing of blood sampling for copeptin measuring (P for subgroup difference ═ 0.85, Figure 6A), methods for copeptin measuring (P for subgroup difference ═ 0.39, Figure 6B), or diagnostic criteria of GDM (P for subgroup difference ═ 0.84, Figure 6C) might significantly affect the association between serum copeptin and GDM, maternal BMI might significantly affect the results (P for subgroup difference ═ 0.0003, Figure 5C). Here, AVP is linked to gestational diabetes.