Prospective cohort study of vitamin D deficiency in pregnancy: Prevalence and limited effectiveness of 1000 IU vitamin D supplementation

Background: Vitamin D deficiency is highly prevalent worldwide among pregnant women. Although vitamin D supplementation is effective in improving vitamin D status, the safety and optimal dosing of vitamin D supplementation during pregnancy remain less well understood.Objective: This study aimed to investigate the prevalence of vitamin D deficiency among pregnant women and evaluate the effectiveness of vitamin D supplementation in improving vitamin D status during pregnancy.Design: This prospective cohort study assessed the impact of a 16-week daily vitamin D supplementation 1000 IU regimen on vitamin D status among pregnant women.Methods: A total of 365 pregnant women were recruited, and their baseline total circulating 25-hydroxy vitamin D concentrations were measured. Of these, 249 participants completed the study, which involved oral daily supplementation with 1000 IU of vitamin D and a repeat of total circulating 25-hydroxy vitamin D concentrations after 16 weeks.Results: The study found that 57.7% of the participants had vitamin D deficiency, consistent with the rates reported in other studies. However, vitamin D supplementation at a dose of 1000 IU had a small effect size and was not clinically significant. However, 67% of participants with vitamin D deficiency remained deficient; among participants initially with vitamin D insufficiency, 30% became deficient. Moreover, 26.5% of individuals with sufficient vitamin D status at 12 weeks showed insufficient levels by 28 weeks.Conclusion: Vitamin D deficiency is widespread among pregnant women, and vitamin D supplementation at a daily dose of 1000 IU may not adequately address this problem. Although the study has limitations, its results align with previous research and may apply to other populations with a high prevalence of vitamin D deficiency during pregnancy. Further research is necessary to determine the most effective approach for addressing prenatal vitamin D deficiency. Prevalence and effectiveness of vitamin D supplementation during pregnancyVitamin D deficiency is common among pregnant women and can lead to various health issues. This study aimed to investigate the effectiveness of vitamin D supplementation in improving vitamin D levels during pregnancy. A total of 365 pregnant women were recruited, and their vitamin D levels were measured at the beginning of the study. The participants were given a daily vitamin D supplement of 1000 IU, and their vitamin D levels were measured at 3-month intervals. The study found that more than half of the participants had vitamin D deficiency, which is consistent with the rates reported in other studies. However, vitamin D supplementation at the given dosage had a small effect and did not significantly increase vitamin D levels in pregnant women. Moreover, vitamin D-rich diets had no significant impact on vitamin D levels. The study emphasizes the importance of identifying effective strategies for preventing and treating vitamin D deficiency during pregnancy. The findings suggest that current strategies advised by international and national guidelines may not be sufficient to address the problem. Further research is needed to identify more effective approaches, including screening, higher safe dosages, and monitoring responses after 3 months of treatment. In summary, vitamin D deficiency is common among pregnant women, and current strategies may not be enough to address the issue. The study highlights the need for effective approaches to prevent and treat vitamin D deficiency during pregnancy, and further research is needed to find these strategies.