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CMAJ Open. 2013 Jun 28;1(2):E77-82. doi: 10.9778/cmajo.20120032. eCollection 2013 May.

Effect of vitamin D status on clinical pregnancy rates following in vitro fertilization.

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Department of Obstetrics and Gynecology, Mount Sinai Hospital, University of Toronto, Toronto, Ont.
Faculty of Medicine, University of Toronto, Toronto, Ont.
Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ont.



Recent studies suggest that vitamin D may play a role in human reproduction. Our goal was to investigate whether vitamin D levels are predictive of implantation and clinical pregnancy rates in infertile women following in vitro fertilization (IVF).


We prospectively evaluated vitamin D status, as determined by serum 25-hydroxy-vitamin D (25[OH]D) levels, in a cohort of 173 women undergoing IVF at Mount Sinai Hospital, Toronto, Ontario. Serum 25(OH)D samples were collected within 1 week before oocyte retrieval. We classified patients as having sufficient (≥ 75 nmol/L) or insufficient (or deficient; hereafter referred to as "insufficient"; < 75 nmol/L) serum levels of 25(OH)D. We compared patient demographics and IVF cycle parameters between groups. The primary outcome measure was clinical pregnancy (intrauterine sac visible on ultrasound performed 4-5 weeks after embryo transfer).


Of the included women, 54.9% had insufficient 25(OH)D levels and 45.1% had sufficient levels. Women with sufficient levels had significantly higher rates of clinical pregnancy per IVF cycle started (52.5%) compared with women with insufficient levels (34.7%; p < 0.001). Implantation rates were also higher in the sufficient 25(OH)D group, but the results were not statistically significant. Multivariable logistic regression analysis (adjusted for age, body mass index and day 5 [v. day 3] embryo transfer) showed that serum 25(OH)D level may be a predictor of clinical pregnancy (adjusted odds ratio 1.01, 95% confidence interval 1.00-1.03).


Our findings suggest that women with sufficient levels of vitamin D are significantly more likely to achieve clinical pregnancy following IVF. Vitamin D supplementation could provide an easy and cost-effective way of improving pregnancy rates; this merits further investigation.


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