Vitamin D deficiency among subfertile women: case-control study

Abstract

Objective: The objective of the study is to compare the dietary vitamin D and calcium intake among subfertile women (cases) versus pregnant women (controls) and to determine the vitamin D levels in the subfertile and pregnant women. The study design was an observational case-control study where a total of 181 (83 previously diagnosed subfertile cases from various causes and 98 pregnant controls) women of reproductive age. A validated questionnaire was used where it focused on key indicators evaluating vitamin D-related factors. Blood was withdrawn for the measurement of serum calcium, albumin and phosphate to exclude secondary causes that might affect vitamin D level.

Results: The prevalence of vitamin D deficiency was significantly higher in the subfertile group than controls (59.0% versus 40.4%; p < 0.01). Calcium supplements intake was significantly higher in controls than the subfertile group (64.6% versus 10.0%; p value < 0.001). Total dietary vitamin D intake (> 400 IU/day) was significantly higher in the controls than the subfertile group.

Conclusion: Vitamin D deficiency is prevalent among subfertile women. Optimization of serum calcium and vitamin D levels is encouraged.

Chinese abstract

目的：本研究目的是比较不孕女性（病例组）和妊娠女性（对照组）饮食中维生素D和钙的摄入量，并确定不孕女性和妊娠女性的维生素D水平。本研究是一项观察性病例对照研究，共入选181位育龄女性为研究对象（其中83位由各种原因引起的不孕症女性为病例组，98未妊娠女性做为对照组）。我们采用调查问卷，主要用于评估维生素D相关因素的关键性指标。抽血检测血清钙、白蛋白及磷酸盐排除可能影响维生素D水平的继发因素。

结果：不孕女性的维生素D缺乏症发生率明显高于对照组(59.0% vs 40.4%; p<0.01)。对照组钙的补充摄入量明显高于不孕组(64.6% vs 10.0%; p<0.001)。对照组膳食中维生素D的总摄入量(≥400 IU/天)明显高于不孕症组。

结论：维生素D缺乏症普遍存在于不孕女性中，应鼓励血清钙及维生素D水平的最优化。

• Calcium
• infertility
• Middle Eastern
• supplementation
• vitamin D

Acknowledgements

The authors are grateful to the staff members who helped in data collection, Suzan Cherian, Dr. ShazaYaseen and Dr. Ahmad Al Badr as well as the participants, Dr. Ahmad Saleh, Dr. Solaiman Al-Obaid and Dr. Mohammed Agdi who were more than enthusiastic to participate in recruiting patients for this study. We also thank Mohammed Bashir for his input on the statistical analysis.

Declaration of interest

The Faculty of Medicine at King Fahad Medical City (KFMC) has funded this study. The authors have nothing to declare.