Related Experiment Video
Updated: Jun 16, 2026

A Method of Trigonometric Modelling of Seasonal Variation Demonstrated with Multiple Sclerosis Relapse Data
Published on: December 9, 2015
Prevalence and Seasonal Variation in Serum 25-Hydroxyvitamin D Concentrations Among Women of Reproductive Age
Background:
This study aimed to investigate serum 25-hydroxyvitamin D [25(OH)D] concentrations among women of reproductive age, stratified by age and season, in order to provide information for vitamin D-related health strategies for this population.
Methods:
A retrospective analysis was conducted on serum 25(OH)D concentrations in women of reproductive age who underwent preconception health examinations at the Physical Examination Department of Haidian District Maternal and Child Health Care Hospital between December 2022 and December 2024. Participants were stratified by age into two groups: advanced maternal age (≥ 35 years) and typical maternal age (< 35 years). Seasonal categorization included spring, summer, autumn, and winter. Intergroup comparisons were performed, and vitamin D nutritional status was classified based on established thresholds.
Results:
A total of 2,325 women were included in the study. The mean serum 25(OH)D concentration was 34.45 ± 11.07 nmol/L. Vitamin D deficiency was observed in 92.47% of participants, insufficiency in 6.24%, and sufficiency in only 1.29%. Participants in the advanced maternal age group demonstrated significantly higher serum 25(OH)D concentrations compared to those in the normal maternal age group (p < 0.05). Seasonal variation in serum 25(OH)D concentrations was observed, with the highest levels recorded during summer and the lowest in spring. Concentrations in summer and autumn were significantly higher than those in winter and spring (p < 0.05); however, no significant differences were found between summer and autumn or between winter and spring (p > 0.05).
Conclusions:
A high prevalence of vitamin D deficiency was observed among women of reproductive age in Haidian District, Beijing, with significant variations by age and season. Routine assessment of serum 25(OH)D concentrations is recommended for women planning pregnancy to facilitate timely and appropriate vitamin D supplementation strategies.
Related Concept Videos
Role of Skin in Vitamin D Synthesis
The solar UV B rays (290-315 nm) are absorbed by the skin, and 7-dehydrocholesterol (provitamin D3) photolyzes it to previtamin D3, which undergoes a rapid transformation to vitamin D3(cholecalciferol).
Bone Disorders
Bone deposition is also affected by the levels of sex hormones like estrogen and testosterone that promote osteoblast activity and bone matrix synthesis. When the level of these hormones decreases due to aging, it causes a reduction in bone deposition. As a result, bone resorption by osteoclasts...
Role of Vitamins in Maintaining Bone Health
Vitamin A
Vitamin A is involved in the process of bone remodeling. Retinoic acid, the active metabolite of Vitamin A, has nuclear receptors in osteoblasts and osteoclasts, which are involved in bone remodeling.
Vitamin B12
Vitamin B12 acts as a cofactor during the formation of osteoblast-related proteins, such as osteocalcin. Vitamin B12 plays a role...
Menopause
Disorders of the Female Reproductive System
Skeleton and Calcium Homeostasis