Vitamin D Deficiency and Associated Factors Among Postpartum Women in Türkiye: A Primary Care Cross-Sectional Study

Background/Objectives: The postpartum period involves substantial physiological changes that may affect maternal vitamin D status. This study aimed to determine serum 25-hydroxyvitamin D [25(OH)D] levels in postpartum women in Konya, Türkiye, and to identify associated factors.

Methods

In this study, 25(OH)D levels were assessed in 267 women aged 18–49 who visited a family health center at 0–1, 6, 12, and 24 months postpartum. Sociodemographic, obstetric, dietary, and lifestyle data were collected using a structured questionnaire, and sun exposure, skin tone, and physical activity level were assessed using standardized methods.

Results

Vitamin D deficiency (<20 ng/mL) was present in 86.9% of participants, and 56.2% reported regular vitamin D supplementation during lactation. In multivariable analysis, serum 25(OH)D levels were significantly higher at 0–1 months [exp(β) = 1.448, 95% CI: 1.165–1.799; p < 0.001] and 6 months postpartum [exp(β) = 1.340, 95% CI: 1.081–1.662; p = 0.008] compared with 12 months postpartum. Older age [exp(β) = 1.021, 95% CI: 1.004–1.037; p = 0.014], vitamin D supplementation during lactation [exp(β) = 1.190, 95% CI: 1.011–1.401; p = 0.036], summer enrollment [exp(β) = 1.441, 95% CI: 1.151–1.805; p = 0.001], and greater sun-exposed body surface area [exp(β) = 1.008, 95% CI: 1.001–1.016; p = 0.025] were independently associated with higher serum 25(OH)D levels.