Fig. 3

Prevalence of vitamin D status by (a) stage of life and (b) season. Classification of vitamin D status (25(OH)D concentration) according to severe deficiency (<15.0 nmol/L), moderate deficiency (15.0–24.9 nmol/L), insufficiency (25.0–49.9 nmol/L), sufficiency (50.0–74.9 nmol/L) and optimal (75.0–124.9 nmol/L); Risk of excess (≥124.9 nmol/L) was not prevalent; (a) Breastfeeding women vs. NPNB women: p = 0.019*; (b) Between season in breastfeeding women: p <0.001*; Between season in NPNB women: p = 0.032*; Breastfeeding women vs. NPNB women in spring: p = 0.498*, summer: p = 0.070*, autumn: p = 0.139*, winter: p = 0.007*; 25(OH)D, 25-hydroxyvitamin D; Autumn, September – November; NPNB, non-pregnant and non-breastfeeding; Spring, March – May; Summer, June – August; Winter, December – February; *Chi-square test