Maternal characteristics of the study population
Maternal characteristics of the study population and the means of maternal 25(OH)D concentrations before 24 weeks of gestation are shown in Table 1. The pregnant women who participated in this study presented a mean of 29.53±4.49 years old. Mean 25(OH)D concentration was 36.85±14.23nmol/L(range from 3-174.3nmol/L). Mean gestational weeks at blood collection was 17.87±3.27 weeks. Among all participants, 192(10.87%), 1023(57.93%), and 551(31.20%) were defined as vitamin D sufficiency, insufficiency, and deficiency, respectively. Figure 2 shows the distribution of vitamin D concentrations in all participants, but there was no significant difference in serum 25(OH)D concentrations between the adverse pregnancy outcomes group and the non-adverse pregnancy outcomes group (P>0.05). Notably,there were 89.13% pregnant women in low vitamin D status.