Figure 1

Association between maternal pre-pregnancy BMI and serum 25(OH)D concentration based on linear regression analyses. (A–C) Stratification analyses by pre-pregnancy BMI. (A) Underweight (<18.5 kg/m2); (B) normal weight (18.5–22.9 kg/m2); (C) overweight (≥23.0 kg/m2). *P < 0.05, **P < 0.01.