Impact of circulating levels of total and bioavailable serum vitamin D on pregnancy rate in egg donation recipients

Objective: To investigate the correlation between total and bioavailable serum 25-OH vitamin D and the pregnancy rate in recipients of donated oocytes.

Design: Retrospective study.

Setting: University-affiliated private IVF center.

Patient(s): A total of 267 patients who were referred to our clinic for oocyte donation from June 2013 to December 2013.

Intervention(s): Serum analysis of vitamin D and bioavailable vitamin D and reproductive outcomes.

Main outcome measure(s): Pregnancy and implantation rate.

Result(s): Among all patients, 15.3% (n = 41) were vitamin D replete (vitamin D >30 ng/mL), 50.2% (n = 134) had vitamin D deficiency (20-30 ng/mL), and 34.4% (n = 92) had insufficient vitamin D (<20 ng/mL). Implantation rates were similar among patients with normal, insufficient, or deficient total serum 25-OH vitamin D levels (61%, 63.4%, and 65.2%, respectively). Pregnancy rates did not differ among the three groups (70%, 69.9%, and 73.9%). Ongoing pregnancy rates were also comparable among the three groups (55.9%, 52.7%, and 60.7%). The predictive value of total vitamin D regarding pregnancy rate was analyzed by the receiver operating characteristic curve, and the area under the curve (AUC) was 0.468. The AUC for bioavailable 25-OH vitamin D was 0.499, showing that the analysis of the AUC for vitamin D or bioavailable vitamin D was not informative.

Conclusion(s): Vitamin D insufficiency and deficiency are frequent conditions in our southern European infertile population. In contrast to previous studies, patients who are not vitamin D replete do not have a decreased chance of becoming pregnant with egg donation. Bioavailable 25-OH vitamin D, which is a better marker of the status than total 25-OH vitamin D, does not correlate with pregnancy rate in recipients of donated oocytes. Thus, at this stage, there is insufficient evidence to recommend vitamin D screening in patients undergoing egg donation.