High Prevalence of Vitamin D Deficiency in Infertile Women Referring for Assisted Reproduction

[Resolution of the national interdisciplinary council of experts "High-dose vitamin D (Devilam) in the practice of an obstetrician-gynecologist"]

On March 28, 2024, the Council of Experts "High-dose vitamin D (Devilam) in the practice of obstetrician-gynecologist, gynecologist and endocrinologist" was held in Moscow with the participation of leading experts gynecologists, endocrinologists and obstetricians-gynecologists, during which new possibilities for the use of high-dose vitamin D in patients of various ages who need correction of existing vitamin D deficiency or insufficiency.

Activity of enzymes in the follicular fluid and outcome of in vitro fertilization

Defining certain parameters of the oocyte microenvironment that can be simply and quickly detected and that enable differentiation of oocytes that have better or worse quality could potentially increase the efficacy of the in vitro fertilization (IVF) method. Follicular fluid represents the microenvironment for the development of oocytes during different stages of maturation. Enzymes present in the follicular fluid may affect the quality of oocytes. There are inconsistencies in the literature concerning enzyme concentration in follicular fluid. The main aim of this study was to examine whether the concentration of enzymes aspartate aminotransferase, alanine aminotransferase (ALT), alkaline phosphatase, and lactate dehydrogenase in follicular fluid can influence the outcome of IVF. The study included 120 patients who were involved in the process of IVF. We used the follicular fluid obtained after follicular aspiration in the ovaries as biological material for the analysis. The values of enzymes LDL (method-kinetic UV test), aspartate aminotransferase (method-kinetic UV test), ALT (method-kinetic UV test) and alkaline phosphatase (method-colorimetric kinetic test) in the follicular fluid were determined on the analyzer АU 680, Becman Coulter. The criteria of the Istanbul consensus of clinical embryologists were used for the embryo assessment. The software package SPSS 20 was used for the statistical processing of data. The results of follicular fluid sample analysis showed a correlation between ALT concentration in the follicular fluid and IVF outcome. Based on our results, we can conclude that ALT concentration affects the outcome of IVF.

Is There a Relevant Clinical Impact in Differentiating Idiopathic versus Unexplained Male Infertility?

PURPOSE

Overall, male factor infertility (MFI) accounts for up to 50% of etiologies of couple's infertility, with almost 30% of MFI cases being idiopathic in nature. Idiopathic MFI does not support a tailored treatment work-up in clinical practice. To investigate rates of and characteristics of men presenting for idiopathic versus unexplained primary infertility as compared with same-ethnicity, age-comparable fertile men.

MATERIALS AND METHODS

Demographic, clinical and laboratory data from 3,098 primary infertile men consecutively evaluated were analyzed and compared with those of 103 fertile controls. Idiopathic male infertility (IMI) was defined for abnormality at semen analysis with no previous history of diseases affecting fertility and normal findings on physical examination and genetic and laboratory testing. Unexplained male infertility (UMI) was defined as infertility of unknown origin with completely normal findings at semen analysis. Descriptive statistics and logistic regression models tested the association between clinical variables and idiopathic infertility status.

RESULTS

Overall, 570 (18.5%) and 154 (5.0%) patients depicted criteria suggestive for either IMI or UMI, respectively. Groups were similar in terms of age, BMI, CCI, recreational habits, hormonal milieu, and sperm DNA fragmentation indexes. Conversely, testicular volume was lower in IMI (p<0.001). Vitamin D3 levels were lower in IMI vs. UMI vs. fertile controls (p=0.01). At multivariable logistic regression analysis only vitamin D3 deficiency (OR, 9.67; p=0.03) was associated with IMI. Characteristics suggestive for IMI versus UMI were observed in almost 20% and 5% of men, respectively. Overall, clinical differences between groups were slightly significant and certainly not supportive of a tailored management work-up.

CONCLUSIONS

Current findings further support the urgent need of a more detailed and comprehensive assessment of infertile men to better tailoring their management work-up in the everyday clinical setting.

Zinc transporters ZIPT-2.4 and ZIPT-15 are required for normal C. elegans fecundity

PURPOSE

The requirement of zinc for the development and maturation of germ lines and reproductive systems is deeply conserved across evolution. The nematode Caenorhabditis elegans offers a tractable platform to study the complex system of distributing zinc to the germ line. We investigated several zinc importers to investigate how zinc transporters play a role in the reproductive system in nematodes, as well as establish a platform to study zinc transporter biology in germline and reproductive development.

METHODS

Previous high throughput transcriptional datasets as well as phylogenetic analysis identified several putative zinc transporters that have a function in reproduction in worms. Phenotypic analysis of CRISPR-generated knockouts and tags included characterization of offspring output, gonad development, and protein localization. Light and immunofluorescence microscopy allowed for visualization of physiological and molecular effects of zinc transporter mutations.

RESULTS

Disruption of two zinc transporters, ZIPT-2.4 and ZIPT-15, was shown to lead to defects in reproductive output. A mutation in zipt-2.4 has subtle effects on reproduction, while a mutation in zipt-15 has a clear impact on gonad and germline development that translates into a more pronounced defect in fecundity. Both transporters have germline expression, as well as additional expression in other cell types.

CONCLUSIONS

Two ZIP-family zinc transporter orthologs of human ZIP6/10 and ZIP1/2/3 proteins are important for full reproductive fecundity and participate in development of the gonad. Notably, these zinc transporters are present in gut and reproductive tissues in addition to the germ line, consistent with a complex zinc trafficking network important for reproductive success.

Vitamin D Deficiency Impacts Exposure and Response of Pravastatin in Male Rats by Altering Hepatic OATPs

This study aimed to determine the effect of vitamin D (VD) deficiency on the efficacy and pharmacokinetics of pravastatin and clarify whether the effects are mediated by Organic anion-transporting polypeptides (OATPs). Experiments were conducted in rats to explore the effect of VD deficiency on the pharmacodynamics and pharmacokinetics of pravastatin. In the pharmacodynamic study, rats were fed a VD-free or VD-supplement high-fat diet for 25–30 days, and plasma 25(OH)VD was dynamically monitored. The response of pravastatin (changes in blood lipids) on rats were then examined after 15 days of pravastatin treatment. In the pharmacokinetic study, rats were fed a VD-free or VD-supplement diet for 25–30 days. The pharmacokinetics of single oral dose pravastatin was then studied, and intestinal and hepatic Oatp1a1 and Oatp2b1 expression was determined using quantitative polymerase chain reaction (qPCR) and western blot. Furthermore, OATP1B1 and OATP2B1 expression in Huh7 cells with or without 1.25(OH)₂D were assessed via qPCR and western blot. For the pharmacodynamic study, the decrease of total cholesterol and increase of high-density lipoprotein cholesterol in VD-deficient rats were smaller than in VD-sufficient rats, indicating that VD deficiency reduced the response of pravastatin in rats. For the pharmacokinetic study, the plasma exposure slightly increased, and liver exposure decreased in VD-deficient rats, but not significantly. VD deficiency decreased the Oatp1a1 and Oatp2b1 expression in the liver, but not in the small intestine. Similarly, OATP1B1 and OATP2B1 protein levels in Huh7 cells were reduced when 1.25(OH)₂D was absent. In conclusion, VD deficiency can decrease the response of pravastatin in rats by reducing the liver pravastatin exposure and expression of hepatic OATPs, consistent with the extended hepatic clearance model theory.

The Effects of Follicular Fluid 25(OH)D Concentration on Intrafollicular Estradiol Level, Oocyte Quality, and Fertilization Rate in Women Who Underwent IVF Program

Objective

25(OH)D (Vitamin D) has been investigated for its role in the process of folliculogenesis and thus affects the quality of oocyte produced by in vitro fertilization. Our aims were to investigate the effects of 25(OH)D levels in follicular fluid, follicular estradiol level, successful fertilization rate in IVF treatment and the correlation between 25(OH)D levels in follicular fluid with the oocyte quality.

Design and Setting

This is an analytic observational study with cross-sectional design conducted between September-November 2018 in two fertility clinics at tertiary hospitals in Bandung, Indonesia.

Participants

The inclusion criteria were women aged 20-35 years who underwent controlled ovarian stimulation in IVF program with normal ovarian reserve and normal BMI. Eligible women were divided into two groups based on their 25(OH)D levels: low and high.

Results

There was a significant difference in oocyte quality (p = 0.03) and follicular estradiol levels (p = 0.02) between the two categories of 25(OH)D levels. High level of 25(OH)D has significantly higher level in comparison with the low level of 25(OH)D. No significant differences were found in terms of successful fertilization rate (p = 0.13). High level of 25(OH)D has higher successful fertilization rate compared to low level of 25(OH)D (71.8% vs 55.26%). A significant positive correlation between 25(OH)D level in follicular fluid and oocyte quality was also found (r = 0.32, p = 0.01).

Conclusion

Women with higher level of 25(OH)D are significantly more likely to have high-quality oocyte and follicular estradiol levels than those with low level of 25(OH)D, although there are no significant results for its relation to successful fertilization rate.

Effects of vitamin D supplementation on ovarian reserve markers in infertile women with diminished ovarian reserve

The purpose of this study was to evaluate the effects of vitamin D supplementation on ovarian reserve markers, including serum anti-Mullerian hormone (AMH) level, follicle-stimulating hormone (FSH) level, and antral follicle count (AFC), in infertile women with diminished ovarian reserve and vitamin D deficiency.A prospective, nonrandomized, cross-sectional study was conducted. Women aged 18 to 41 years who were unable to become pregnant after 12 months of sexual intercourse and had normal tubal patency, partners with normal semen analysis, diminished ovarian reserve, and 25-hydroxyvitamin D [25(OH)D] deficiency were included. Eligible patients' AFC and serum levels of AMH, FSH, 25(OH)D, 1,25-dihydroxyvitamin D [1,25(OH)D], calcium, phosphate, alkaline phosphatase, and parathormone were assessed before and after administration of 300,000 IU of vitamin D ampules. Changes in the parameter values after vitamin D supplementation were compared with the initial levels.The study was conducted in 62 of the 142 participants. The AFC and AMH, 25(OH)D, 1,25(OH)D, phosphate (P < .01), and calcium levels (P < .05) were statistically significantly increased after vitamin D supplementation. Statistically significant decreases in FSH (P < .01) and alkaline phosphatase levels (P < .05) were observed after vitamin D supplementation. No statistically significant correlations were found between 25(OH)D level and AFC, 1,25(OH)D level, AMH level, and FSH level before and after supplementation (P > .05).As improvements in the ovarian reserve markers were obtained with vitamin D supplementation, vitamin D might be considered as a fertility treatment for patients with diminished ovarian reserve and vitamin D deficiency.

Effect of Vitamin D Supplementation on In Vitro Fertilization Outcomes: A Trial Sequential Meta-Analysis of 5 Randomized Controlled Trials

Despite numerous studies indicating an imperative role of vitamin D for reproduction, the importance of vitamin D supplementation on in vitro fertilization (IVF) outcomes remains controversial. We therefore performed this meta-analysis to investigate the IVF outcomes of vitamin D supplementation in infertile women with vitamin D deficiency. We systematically searched PubMed, Embase and the Cochrane library for identifying all relevant studies published before August 2021. Pregnancy rate was defined as the primary outcome while good quality embryo, fertilization rate, ongoing pregnancy, and miscarriage were secondary outcomes. We used Review Manager 5.3 (RevMan) to conduct meta-analysis and examined the robustness of the primary outcome by trial sequential analysis. Five studies were included in the final analysis and it suggested that vitamin D supplementation was associated with improved chemical pregnancy rate (risk ratio [RR] = 1.53, 95% confidence interval [CI] = 1.06 to 2.20, p = 0.02) but not benefited in improving clinical pregnancy rate (RR = 1.34, 95% CI = 0.81 to 2.24, p = 0.25) and all secondary outcomes. Trial sequential analysis suggested further studies are needed to confirm this conclusion. We concluded that vitamin D supplementation should be prescribed to improve chemical pregnancy in infertile women with vitamin D deficiency and more studies are required to further confirm this finding.

Single oral dose of vitamin D3 supplementation prior to in vitro fertilization and embryo transfer in normal weight women: the SUNDRO randomized controlled trial

BACKGROUND

Improving in vitro fertilization success is an unmet need. Observational studies have suggested that women with deficient or insufficient vitamin D have lower chances of in vitro fertilization success, but whether supplementation improves clinical pregnancy rate remains unclear.

OBJECTIVE

This study aimed to determine whether oral vitamin D₃ supplementation improves clinical pregnancy in women undergoing an in vitro fertilization cycle.

STUDY DESIGN

The "supplementation of vitamin D and reproductive outcome" trial is a 2-center randomized superiority double-blind placebo-controlled trial. Subjects were recruited between October 2016 and January 2019. Participants were women aged 18 to 39 years with low vitamin D (peripheral 25-hydroxyvitamin D of <30 ng/mL), serum calcium of ≥10.6 mg/dL, body mass index of 18 to 25 kg/m², and antimüllerian hormone levels of >0.5 ng/mL and starting their first, second, or third treatment cycle of conventional in vitro fertilization or intracytoplasmic sperm injection. The primary outcome was the cumulative clinical pregnancy rate per cycle. Pregnancies obtained with both fresh or frozen embryo transfers were included. Clinical pregnancy was defined as an intrauterine gestational sac with a viable fetus. The primary analysis was performed according to the intention-to-treat principle and could also include natural conceptions. Secondary outcomes included total dose of gonadotropins used, embryologic variables (number of oocytes retrieved, number of suitable oocytes retrieved, fertilization rate, and rate of top-quality embryos), and clinical outcomes (miscarriage rate and live birth rate).

RESULTS

Overall, 630 women were randomized 2 to 12 weeks before the initiation of the in vitro fertilization cycle to receive either a single dose of 600,000 IU of vitamin D₃ (n=308) or placebo (n=322). Interestingly, 113 (37%) and 130 (40%) women achieved a clinical pregnancy in the treatment and placebo groups, respectively (P=.37). The risk ratio of clinical pregnancy in women receiving vitamin D₃ was 0.91 (95% confidence interval, 0.75-1.11). Compared with the placebo, vitamin D₃ supplementation did not improve the rate of clinical pregnancy. Exploratory subgroup analyses for body mass index, age, indication to in vitro fertilization, ovarian reserve, interval between drug administration and initiation of the cycle, and basal levels of 25-hydroxyvitamin D failed to highlight any clinical situation that could benefit from the supplementation.

CONCLUSION

In women with normal weight with preserved ovarian reserve and low vitamin D levels undergoing in vitro fertilization cycles, a single oral dose of 600,000 IU of vitamin D₃ did not improve the rate of clinical pregnancy. Although the findings do not support the use of vitamin D₃ supplementation to improve in vitro fertilization success rates, further studies are required to rule out milder but potentially interesting benefits and explore the effectiveness of alternative modalities of supplementation.

Oral Vitamin D supplementation impacts gene expression in granulosa cells in women undergoing IVF

STUDY QUESTION

Does oral Vitamin D supplementation alter the hormonal milieu of follicular fluid (FF) and the transcriptomic profile of luteinised granulosa cells (GCs) in women with Vitamin D deficiency undergoing IVF?

SUMMARY ANSWER

A transcriptomic signature relevant to oral Vitamin D supplementation in luteinised GCs was demonstrated, although Vitamin D supplementation did not alter hormone levels in FF.

WHAT IS KNOWN ALREADY

Vitamin D deficiency is linked to lower live birth rates among women undergoing IVF. It is unclear whether Vitamin D elicits a targeted action in reproductive physiology or is a surrogate marker of overall well-being. Several in-vitro studies, but none in vivo, have examined the impact of Vitamin D on the periovulatory follicle, focusing on GCs as a proxy marker of oocyte competence.

STUDY DESIGN, SIZE, DURATION

We present a report of secondary outcomes from the SUNDRO clinical trial, which was launched in 2016 to determine whether Vitamin D supplementation can improve the IVF outcomes of women who are deficient in Vitamin D (<30 ng/ml). FF samples of 145 women who were randomised to receive Vitamin D or placebo from March 2017 to January 2019 were collected. All follicles that were aspirated in our study measured ≥11 mm on the day of hCG trigger. The first cohort of samples was collected from the dominant follicle of each participant and utilised for hormone profiling (n = 50 Vitamin D, n = 45 Placebo). For the second cohort, the follicle aspirates of each participant were pooled to create a single FF sample, which was used for the isolation of GCs for gene expression studies (n = 20 Vitamin D, n = 30 placebo). Six of the samples from the second cohort were used for RNA-sequencing analysis (n = 3 Vitamin D, n = 3 placebo).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Two academic infertility units were involved in the recruitment of the participants, who received a single dose of oral 25-hydroxyvitamin D (600 000 IU) or placebo, 2-12 weeks before oocyte retrieval. Women in both groups were deficient in Vitamin D, aged 18-39 years with a normal BMI (18-25 kg/m2) and <3 previous IVF cycles. The FF was aspirated at the time of oocyte retrieval and stored. Liquid chromatography tandem mass spectrometry was used to measure FF abundance of 25-hydroxyvitamin D, aldosterone, androstenedione, cortisol, cortisone, corticosterone, 11-deoxycorticosterone, 11-deoxycortisol, 21-deoxycortisol, dehydroepiandrosterone, dehydroepiandrosterone sulfate, dihydrotestosterone, oestradiol (E2), 17-OH-hydroxyprogesterone, progesterone (P4) and testosterone. GCs were isolated from pooled FFs and the transcriptome was evaluated by RNA-sequencing and RT-PCR. Ingenuity pathway analysis (IPA) was used to assess the top canonical pathways and upstream regulators mediating the action of Vitamin D.

MAIN RESULTS AND THE ROLE OF CHANCE

At oocyte retrieval, FF concentration of 25-hydroxyvitamin D was 2.8-fold higher (P < 0.001) in the Vitamin D group (39.5 ng/ml; n = 50) compared to placebo (13.8 ng/ml; n = 45) but no other hormonal differences were detected. In the placebo group, but not the Vitamin D group, weak correlations of 25-hydroxyvitamin D concentration with P4 (r = 0.31, P = 0.03) and E2 (r = 0.45, P = 0.002) were observed. RNA-sequencing identified 44 differentially expressed genes in the GCs of patients who received Vitamin D (n = 3) compared to placebo (n = 3). RT-PCR demonstrated upregulation of VDR (vitamin D receptor), GSTA3 (glutathione S-transferase A3) and IL21R (interleukin 21 receptor), and downregulation of P T GS2 (prostaglandin-endoperoxide synthase 2), KLF4 (kruppel-like factor 4), T RP C4 (transient receptor potential cation channel subfamily C member 4), VEGF (vascular endothelial growth factor), RXRB (retinoid X receptor beta) and AGER (advanced glycosylation end-product specific receptor) genes in the Vitamin D (n = 17) versus placebo (n = 27) group. IPA suggested roles of Vitamin D in antioxidant defence.

LIMITATIONS, REASONS FOR CAUTION

Interpretation of the data is influenced by our intervention strategy (2-12 weeks prior to retrieval). As folliculogenesis may last 5-6 months, our protocol can only examine with confidence the impact of Vitamin D on the final stages of follicular growth. Furthermore, we examined the hormonal profile of the dominant follicle only, while the GC data reflect the transcriptome of all (pooled) follicles large enough to be used for IVF. Luteinised GCs from controlled ovarian stimulation were used in this study, which may be functionally distinct from the GCs of developing follicles. Moreover, the sample size for RNA-sequencing analysis was low (n = 3 per group), regardless of validation by RT-PCR that was performed on a larger cohort, introducing complexity to the IPA analysis, which required an input of data with P-adjusted <0.08 instead of <0.05 to be informative.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first in-vivo study to show that Vitamin D supplementation alters gene expression in luteinised GCs. In contrast to some in-vitro evidence, no effect of the intervention on expression of genes encoding steroidogenic enzymes was observed. Unlike other studies, our results suggest that supplementation with Vitamin D is unlikely to directly influence hormone availability in FF. Our findings instead reinforce the hypothesis that Vitamin D could be considered one of the gatekeepers in protecting against an exaggerated response to ovarian stimulation.

STUDY FUNDING/COMPETING INTEREST(S)

The study has been funded by the Italian Ministry of Health (RF-2013-02358757) following peer review in the competitive 'Bando di Ricerca Finalizzata e Giovani Ricercatori 2013' for the clinical trial SUNDRO (EudraCT registration number 2015-004233-27). There are no competing interests.

TRIAL REGISTRATION NUMBER

EudraCT registration number 2015-004233-27.

Positive effect of a new supplementation of vitamin D3 with myo-inositol, folic acid and melatonin on IVF outcomes: a prospective randomized and controlled pilot study

To assess whether oral supplementation of vitamin D₃, myo-inositol, folic acid and melatonin affects IVF outcomes. One hundred and twenty consecutive infertile women attending IVF treatment were 1:1 randomly distributed in two groups. Women in group A (control) were assigned to receive myo-inositol, alpha-lactalbumin and folic acid in the morning, and myo-inositol, folic acid and melatonin in the evening. Women in group B (treated) were assigned to receive analogous treatment, with the addition of cholecalciferol (vitamin D₃) in the evening from the early beginning of the luteal phase. 50 patients in group A and 50 in group B underwent blastocyst transfer and were considered in the statistical analysis. Vitamin D₃ levels significantly increased after 45 days of treatment: 33.2 ng/ml in group B Vs. 24.3 ng/ml in group A (p < .0001). The implantation rate increased as well: 37.1% in group B Vs. 19.2% in group A (p < .0151). Overall, the results indicate that increased vitamin D₃ levels positively correlate with the implantation rate in IVF. Because of the low number of participants, these findings need to be confirmed with larger cohorts of patients.

[Vitamin D and reproductive health]

Vitamin D insufficiency and deficiency in women with infertility is more common than in the population. However, we still do not know the exact mechanisms for the participation of vitamin D in the regulation of reproductive function. The purpose of this study is to analyze actual literature data on the role of vitamin D in the regulation of reproductive system and its influence on using of assisted reproductive technologies for the treatment of infertility. A search was carried out for literary sources published in the NSBI database PubMed, Medline, and others with a search depth of up to 20 years. 135 sources on this topic were studied, of which 54 were included in the analysis. The review presents data obtained in animal studies, in vitro and in clinical studies. Thus, the absence of vitamin D resulted in a dramatical decrease in fertility in both female and male rats and mice, due to the development of hypocalcemia. In vitro studies describe its involvement in the receptive transformation of the endometrium and in the regulation of the immune response during embryo implantation. However, clinical studies often show conflicting results. There is no unequivocal data on the effect of vitamin D levels on spermogram parameters, but a decrease in the pregnancy rate was shown when ovulation was induced in pairs, where a vitamin D deficiency was revealed in men. A meta-analysis published in 2017 showed a decrease in the pregnancy and live birth rate in women with low levels of vitamin D after the use of assisted reproductive technologies (ART). It was not possible to establish whether this decrease depends on oocyte quality or endometrium. There is an opportunity that the effect of vitamin D deficiency on fertility will not come with all forms of infertility. For example, in women with anovulation due to polycystic ovary syndrome, vitamin D deficiency is demonstrated to decrease pregnancy rate in ovulation induction cycles and in ART. Such relationship was not found in women with unexplained infertility.Thus, the role of vitamin D in the pathogenesis of infertility requires further study, as well as the possibilities of therapy in order to increase the effectiveness of infertility treatment methods and assisted reproductive technology programs.

Normal fertilisation rates and serum 25-OHD levels among couples undergoing in-vitro fertilisation: a prospective cohort study

Background

The aim of this study was to explore the correlation between serum vitamin D levels in couples undergoing in-vitro fertilisation (IVF) and normal fertilisation process.

Methods

Between March 2016 and March 2017, we performed a prospective cohort study at an academic reproductive medicine centre to measure serum 25-hydroxyvitaminD (25-OHD) levels of 1232 couples before controlled ovarian stimulation. Generalized linear regression and binary multivariate logistic regression were employed to assess whether 25-OHD levels in men and women correlated with normal fertilisation rates and low fertilisation rate (LFR).

Results

Serum 25-OHD levels in women were classified into three groups: Group A, less than 10%; Group B, between 10 and 90%; and Group C, greater than 90%. Using generalized linear regression, we observed that female 25-OHD levels were related to normal fertilisation rates. Adjusted normal fertilisation rates from Group A to Group C in women were 59.50, 62.72, and 66.13%, respectively (P = 0.007). After binary logistic regression analysis, for women, compared with Group C, the ORs for LFR were 4.814 in Group A (95% CI, 1.266–18.309, P = 0.021) and were 3.204 in Group B (95% CI, 0.949–10.812, P = 0.061). Male 25-OHD levels were not related to the probability of low fertilisation rate (P > 0.05).

Conclusions

Circulating 25-OHD concentrations in women appear to be associated with normal fertilisation rates and low fertilisation rates in IVF cycles, but not in men. A further randomized controlled trial with vitamin D supplementation is needed to demonstrate whether female vitamin D levels exert an effect on the normal fertilisation process.

Trial registration

https://clinicaltrials.gov/;NCT03305510; Registered 08 October 2017 - Retrospectively registered.

Association between vitamin D and endometriosis: a systematic review

BACKGROUND

Endometriosis is one of the most common gynecological diseases of reproductive age, with a prevalence of 5-10% and grave consequences for quality of life and fertility. Vitamin D (vit D), a classic regulator of plasma calcium concentration and skeleton mineralization, is also an effective modulator of the immune system. Several studies suggest that immunologic properties attributed to vit D along with vit D receptor (VDR) expression in reproductive tissues may be involved in the pathogenesis of endometriosis.

OBJECTIVE

To systematically review the literature for the association between components of vit D metabolism and endometriosis.

MATERIALS AND METHODS

A systematic review of the literature published in the Medline and Cochrane Central databases was conducted for original research articles on humans, published in any language.

RESULTS

Twenty-one studies were included in the systematic review. Among them, 12 examined the relationship of endometriosis with vit D metabolites, eight with vit D-binding protein (VDBP), three with VDR polymorphisms, and two with vit D regulatory enzymes. There are discrepancies between the outcomes of the available literature publications.

CONCLUSIONS

This is a systematic attempt to collect, evaluate, and present the known data on the association between vit D and endometriosis. Given the heterogeneity and the diversity of the present studies, more research is required to elucidate the association between vit D and endometriosis.

Vitamin D status in endometriosis: a systematic review and meta-analysis

PURPOSE

No consensus exists on the relationship between vitamin D status and endometriosis. The chief aim of our study was to evaluate the association between serum vitamin D levels and endometriosis.

METHODS

We searched for MEDLINE, EMBASE, and China National Knowledge Infrastructure (CNKI) databases for studies elucidated the circulating vitamin D levels in endometriosis. The standardized mean differences (SMDs) or odds ratios (ORs) with their 95% confidence interval (CIs) were calculated to evaluate the association between vitamin D levels and endometriosis.

RESULTS

Nine studies were included in this meta-analysis. The pooled results indicated that women with endometriosis had lower vitamin D status than that in controls (SMD - 0.97 ng/mL, 95% CI - 1.80 to - 0.14; p = 0.02), and vitamin D status had a negative correlation with the severity of the disease (stage III-IV vs stage I-II: SMD - 1.33 ng/mL, 95% CI - 2.54 to - 0.12; p = 0.03). Although it was not statistically significantly different, hypovitaminosis D had a tendency to be associated with endometriosis (OR 2.77, 95% CI 0.85-6.08, p = 0.10). Heterogeneity was high among included studies. Subgroup analyses revealed that women with no hormone use had lower vitamin D status when compared with controls (SMD - 1.38 ng/mL, 95% CI - 2.59 to - 0.18; p = 0.02). For studies which sample size < 100, serum vitamin D levels were significantly lower in patients than that in controls (SMD - 0.65 ng/mL, 95% CI - 1.19 to - 0.11; p = 0.02).

CONCLUSIONS

Women with endometriosis had lower vitamin D status when compared with controls, and a negative relationship between vitamin D levels and severity of endometriosis was observed. In addition, hypovitaminosis D was a potential risk factor for endometriosis.

Roles of Vitamin D in Reproductive Systems and Assisted Reproductive Technology

Vitamin D, an essential steroid hormone in the human body, plays an important role in not only the regulation of calcium and phosphorus metabolism, but also in various physiological processes, such as cell differentiation and apoptosis, inflammation, and insulin resistance. Vitamin D receptors are widely distributed in male and female reproductive systems, suggesting that vitamin D is essential for fertility. Because vitamin D deficiency is highly prevalent around the world, this review aims to discuss the potential functions of vitamin D in male and female reproductive systems and the associations between vitamin D and assisted reproductive technology (ART) outcomes. Vitamin D is involved in many physiological reproductive processes, including steroidogenesis, spermatogenesis, and acrosome reaction. It is correlated with sperm quality, ovarian reserve, polycystic ovarian syndrome, and endometriosis, among others. Controversial clinical findings on vitamin D levels and ART outcomes were revealed in this review, and demonstrations of efficacy for human fertility in randomized controlled trials of vitamin D supplementation are notably lacking. Thus, further studies are highly required involving molecular mechanisms among different species and human populations, as well as randomized controlled trials.

The effect of vitamin D status on ovarian reserve markers in infertile women: A prospective cross-sectional study

Background

Vitamin D deficiency and infertility are two important health problems in Iran. Some studies suggest that vitamin D may influence Anti-Müllerian hormone (AMH) and antral follicle count (AFC) as an ovarian reserve.

Objective

The present study aimed to investigate the impact of vitamin D on AMH serum concentrations/AFC.

Materials and Methods

Three hundred and five infertile women referred to the IVF Unit of Yas hospital, between July and December 2017, were enrolled in this cross-sectional study. The demographic characteristics of the participants, as well as the serum levels of vitamin D, AMH, and ultrasonic examination of AFC were recorded.

Results

Finally, 287 infertile women were included in the analysis with a mean age of 29.95 ± 4.73 yr (18-45 yr) and a mean Body mass indexof 25.11 ± 4.41 kg/m 2 . The median AMH and vitamin D levels were 3.20 and 22.82 ng/ml, respectively. Considering the cut-off level of 20 ng/ml, 58.7% were vitamin D deficient. Regression analysis showed no association between AMH and vitamin D levels (p = 0.161), even after adjusting for baseline variables (p = 0.182). A total of 120 patients had an AFC < 6 and 164 ≥ 6, which was not statistically different between the groups with normal level or deficient vitamin D (p = 0.133).

Conclusion

The present cross-sectional study showed no significant association between serum levels of vitamin D and AMH or AFC in infertile women, even after adjusting for baseline variables.

Effects of vitamin D on drugs: Response and disposal

Vitamin D supplementation and vitamin D deficiency are common in clinical experience and in daily life. Vitamin D not only promotes calcium absorption and immune regulation, but also changes drug effects (pharmacodynamics and adverse reactions) and drug disposal in vivo when combined with various commonly used clinical drugs. The extensive physiological effects of vitamin D may cause synergism effects or alleviation of adverse reactions, and vitamin D's affect on drugs in vivo disposal through drug transporters or metabolic enzymes may also lead to changes in drug effects. Herein, the effects of vitamin D combined with commonly used drugs were reviewed from the perspective of drug efficacy and adverse reactions. The effects of vitamin D on drug transport and metabolism were summarized and analyzed. Hopefully, more attention will be paid to vitamin D supplementation and deficiency in clinical treatment and drug research and development.

Effect of vitamin D supplementation on assisted reproduction technology (ART) outcomes and underlying biological mechanisms: protocol of a randomized clinical controlled trial. The "supplementation of vitamin D and reproductive outcome" (SUNDRO) study

Background

Vitamin D plays an important role in human physiology and pathology. The receptor for vitamin D regulates 0.5–5% of the human genome. Accordingly, vitamin D insufficiency has been shown to increase the risk of several diseases. In recent years, based on growing evidence, on a role of vitamin D has been also postulated in reproductive health both in animals and humans, especially in female fertility female fertility. In vitro fertilization success was shown to be higher in women with appropriate reserves of vitamin D. However a causal relation has not been demonstrated and randomized controlled trials testing the effectiveness of vitamin D supplementation in IVF are warranted.

Methods

This is a multicenter randomized double blinded placebo controlled study aimed at determining the benefits of vitamin D [25(OH)D] supplementation in improving clinical pregnancy rate in women undergoing IVF. Eligible women with a serum level of 25-hydroxyvitamin D [25(OH)D] < 30 ng/ml will be randomized. Recruited women will be given the drug (either 600,000 IU of 25(OH) D or placebo in a single oral administration) at the time of randomization. Two centres will participate and the sample size (700 women) is foreseen to be equally distributed between the two. Patients will be treated according to standard IVF protocols.

Discussion

The primary aim of the study is the cumulative clinical pregnancy rate per oocyte retrieval. Clinical pregnancy is defined as the presence of at least one intrauterine gestational sac with viable foetus at first ultrasound assessment (3 weeks after a positive human chorionic gonadotropin [hCG] assessment). Secondary outcomes include: 1) clinical and embryological variables; 2) oocyte and endometrium quality at a molecular level. To investigate this latter aspect, samples of cumulus cells, follicular and endometrial fluids will be obtained from a subgroup of 50 age-matched good-prognosis cases and controls.

Trial registration

The protocol was included in EudraCT on 22nd September 2015 with the registration number assigned ‘2015-004233-27’; it was submitted through the database of the Italian “Osservatorio Nazionale della Sperimentazione Clinica (OsSC)” - (National Monitoring Centre of Clinical Trials) to the National Competent Authority on 8th March 2016 and approved on 23rd June 2016.

High prevalence of vitamin D deficiency in Turkish women undergoing in vitro fertilization: A descriptive study

The authors' aim in this study was to determine the vitamin D levels of Turkish women who were undergoing in vitro fertilization (IVF). The study design was a descriptive cohort study of a total of 208 infertile women at an IVF center in Turkey. Our findings showed that 4.3% of the women had a replete vitamin D level, 23.6% of the women had insufficient vitamin D levels, and 72.1% of women had deficient vitamin D levels. Our findings suggest that much more effective vitamin D support programs should be implemented for women who are seeking to become pregnant.

Effect of Vitamin D Supplementation on Intracytoplasmic Sperm Injection Outcomes: A Randomized Double-Blind Placebo-Controlled Trial

Background

Despite numerous studies indicating an imperative role for reproduction, however, the role of Vitamin D supplementation on outcomes of assisted reproductive techniques remains controversial. This clinical trial was per- formed to evaluate the effect of Vitamin D supplementation 6 weeks prior to intracytoplasmic sperm injection (ICSI) on fertility indices.

Materials and Methods

The present study was a double-blind clinical trial conducted on infertile women was ran- domly allocated into two groups: Vitamin D supplementation (42 participants) and placebo (43 participants). Serum Vitamin D was measured before and six to eight weeks after treatment, on the day of ovum pick up. Results were analyzed using SPSS16 and fertility indices were compared between the two groups.

Results

No significant difference was observed between the intervention and control groups regarding the mean number of oocytes retrieved, percentage mature oocyte, fertilization rate and the rate of good quality embryos (all P>0.05). But, percentages of the individual with suitable endometrium (7-14 mm thickness) were significantly higher in the Vitamin D compared to control group (P=0.011). The rate of chemical (47.6 vs. 25.5%, P=0.013) and clinical pregnancy rate (38.1 vs. 20.9%, P=0.019) were also significantly higher in the Vitamin D compared to control group.

Conclusion

The present study reveals that consuming Vitamin D for 6 weeks prior to ICSI improves quality of endo- metrium, rate of chemical and clinical pregnancy (Registration Number: IRCT2015111124999N1).

Evaluating the effects of administration of 25-hydroxyvitamin D supplement on serum anti-mullerian hormone (AMH) levels in infertile women

The aim of the study was to evaluate the effects of administration of 25-hydroxyvitamin D [25(OH) D] on serum antimullerian hormone (AMH) levels in infertile women. The study was performed as a non-randomized clinical trial on 30 infertile women who had low serum level of both 25(OH) D and anti-mullerian hormone. Vitamin D was prescribed 50,000 IU weekly for up to three months for all eligible participants. Serum levels of both 25(OH) D and AMH have increased significantly after treatment with 25(OH) D. There was a significant correlation between serum levels of 25(OH) D after treatment with AMH (p = .029, OR = 2.9, CI 95% = 2.7-5.5). Mean AMH level after treatment was higher in women with sufficient 25(OH) D, than women with insufficient 25(OH) D (1.048 ± 0.644 vs. 0.513 ± 0.284 ng/ml), which shows a significant difference (p = .043). Also, after treatment, in women with mean AMH level of >0.7 ng/ml (19 women), mean level of 25(OH) D was higher than in women with mean AMH level of <0.7 ng/ml (11 women) (59.332 ± 21.751 vs. 38.881 ± 17.281 ng/ml, p = .013). This means that higher levels of 25(OH) D are accompanied with higher levels of AMH. In conclusions with administration and increasing the amount of vitamin D serum levels, the serum levels of AMH have increased.

Hair Trace Element and Electrolyte Content in Women with Natural and In Vitro Fertilization-Induced Pregnancy

The objective of the present study was to perform comparative analysis of hair trace element content in women with natural and in vitro fertilization (IVF)-induced pregnancy. Hair trace element content in 33 women with IVF-induced pregnancy and 99 age- and body mass index-matched control pregnant women (natural pregnancy) was assessed using inductively coupled plasma mass spectrometry. The results demonstrated that IVF-pregnant women are characterized by significantly lower hair levels of Cu, Fe, Si, Zn, Ca, Mg, and Ba at p < 0.05 or lower. Comparison of the individual levels with the national reference values demonstrated higher incidence of Fe and Cu deficiency in IVF-pregnant women in comparison to that of the controls. IVF pregnancy was also associated with higher hair As levels (p < 0.05). Multiple regression analysis revealed a significant interrelation between IVF pregnancy and hair Cu, Fe, Si, and As content. Hair Cu levels were also influenced by vitamin/mineral supplementation and the number of pregnancies, whereas hair Zn content was dependent on prepregnancy anthropometric parameters. In turn, planning of pregnancy had a significant impact on Mg levels in scalp hair. Generally, the obtained data demonstrate an elevated risk of copper, iron, zinc, calcium, and magnesium deficiency and arsenic overload in women with IVF-induced pregnancy. The obtained data indicate the necessity of regular monitoring of micronutrient status in IVF-pregnant women in order to prevent potential deleterious effects of altered mineral homeostasis.

A systematic review of vitamin D status in southern European countries

PURPOSE

Despite an acknowledged dearth of data on serum 25-hydroxyvitamin D (25(OH)D) concentrations from Southern European countries, inter-country comparison is hampered by inconsistent data reporting. The purpose of the current study was to conduct a systematic literature review of available data on serum 25(OH)D concentrations and estimate vitamin D status in Southern European and Eastern Mediterranean countries, both at a population level and within key population subgroups, stratified by age, sex, season and country.

METHODS

A systematic review of the literature was conducted to identify and retrieve scientific articles reporting data on serum 25(OH)D concentration and/or vitamin D status following standard procedures.

RESULTS

Data were extracted from 107 studies, stratified by sex and age group, representing 630,093 individuals. More than one-third of the studies reported mean 25(OH)D concentrations below 50 nmol/L and ~ 10% reported mean serum 25(OH)D concentrations below 25 nmol/L. Overall, females, neonates/ infants and adolescents had the higher prevalence of poor vitamin D status. As expected, there was considerable variability between studies. Specifically, mean 25(OH)D ranged from 6.0 (in Italian centenarians) to 158 nmol/L (in elderly Turkish men); the prevalence of serum 25(OH)D < 50 nmol/L ranged from 6.8 to 97.9% (in Italian neonates).

CONCLUSIONS

Contrary to expectations, there was a high prevalence of low vitamin D status in the Southern Europe and the Eastern Mediterranean regions, despite abundant sunshine. These data further emphasize the need for strategies, such as fortification of foods with vitamin D and/or vitamin D supplementation, which will be tailored to the needs of specific population groups with higher risk of insufficiency or deficiency, to efficiently tackle the pandemic of hypovitaminosis D in Europe.

The importance of vitamin D in maternal and child health: a global perspective

Vitamin D and calcium are important nutrients for skeletal growth and bone health. Children and pregnant women are particularly vulnerable to 25-hydroxy vitamin D deficiency (VDD). VDD, with or without dietary calcium deficiency, can lead to nutritional rickets (NR), osteomalacia, and disturbances in calcium homeostasis. Multiple studies have linked VDD to adverse health outcomes in both children and pregnant women that extend beyond bone health. VDD remains an important global public health concern, and an important differentiation must be made between the impact of VDD on children and adults. Reports of increased incidence of NR continue to emerge. NR is an entirely preventable condition, which could be eradicated in infants and children worldwide with adequate vitamin D and calcium supplementation. The desire and necessity to put in place systems for preventing this potentially devastating pediatric disease should not elicit dispute. VDD and NR are global public health issues that require a collaborative, multi-level approach for the implementation of feasible preventative strategies. This review highlights the history, risk factors, and controversies related to VDD during pregnancy and childhood with a particular focus on global NR prevention.

Concordance of vitamin D peripheral levels in infertile couples' partners

A large number of evidence supports the role of vitamin D insufficiency in both women and men infertility. However, no studies have evaluated the rate of concordance of vitamin D status between the partners. This finding might open new scenarios in the interpretation of the available data linking vitamin D insufficiency and infertility. In the present cross-sectional study, 103 consecutive infertile couples were recruited between April and May 2014. Both partners concomitantly provided a serum sample for the assessment of 25-hydroxy-vitamin D [25-(OH)-D]. Vitamin D insufficiency was defined as serum 25-(OH)-D <20 ng/ml. One hundred-fifty subjects (73 women and 77 males) were 25-(OH)-D insufficient, corresponding to a rate of 73%. Overall, concordance was observed in 73 couples (71%), thus higher than the expected 61% (0.732 + 0.272) based on chance (p = 0.007). The Pearson coefficient of correlation R2 between the partners of the couples was 0.52 (p < 0.001). No statistically significant differences emerged when evaluating the rate of 25-(OH)-D insufficiency according to the causes of infertility. Serum 25-(OH)-D correlates within the partners of infertile couples. Further evidence is warranted to determine the clinical relevance and possible clinical applications of this finding.

Effects of Vitamin D on Endometriosis-Related Pain: A Double-Blind Clinical Trial

Background

Endometriosis is a disabling disease of reproductive-age women. Dysmenorrhea, dyspareunia, and pelvic pain are the main symptoms of endometriosis. Its etiology is not clear. Endometriosis may have various causes, including vitamin D deficiency, but its effect is controversial.

Material/Methods

In this double-blind clinical trial, we enrolled patients with endometriosis diagnosed and treated by laparoscopy, with scores of at least 3 for of dysmenorrhea and/or pelvic pain at 8 weeks after surgical treatment. They were randomly prescribed vitamin D (50 000 IU weekly for 12 weeks) or placebo. Severity of pain in the 2 groups (placebo and treatment) was compared by VAS test at 24 weeks after surgical treatment.

Results

There were 19 patients in the vitamin D group and 20 in the placebo group. Baseline characteristics in the 2 groups were similar. Following the treatment with vitamin D or placebo, we did not find significant differences in severity of pelvic pain (p=0.24) and dysmenorrhea (p=0.45) between the 2 groups. Mean pelvic pain at 24 weeks after laparoscopy in the vitamin D group was 0.84±1.74 and in placebo group it was 0.68±1.70 (p=0.513). Mean dysmenorrhea was 2.10±2.33 in the vitamin D group and 2.73±2.84 in the placebo group (p=0.45).

Conclusions

After ablative surgery for endometriosis, vitamin D treatment did not have a significant effect in reducing dysmenorrhea and/or pelvic pain.

Low vitamin D3 and high anti-Müllerian hormone serum levels in the polycystic ovary syndrome (PCOS): Is there a link?

OBJECTIVES

Low vitamin D serum level has been reported in women with polycystic ovary syndrome (PCOS) compared to controls. A few in vitro studies showed that the bioactive form of vitamin D is able to modulate the expression of the anti-Müllerian hormone (AMH) gene. However, in vivo studies failed to demonstrate clearly whether low vitamin D3 serum level is involved in the AMH excess of PCOS. This prospective study evaluates serum vitamin D3 and AMH levels in women with PCOS and in controls, before and after vitamin D supplementation.

MATERIALS AND METHODS

Among vitamin D deficient patients, 23 patients with PCOS were compared to 27 women with normal ovarian reserve (NOR). The vitamin D deficient patients received a vitamin D supplementation according to the depth of their insufficiency. For the 23 patients with PCOS and the 27 controls, serum AMH assay and serum calciotropic hormone assays [25-hydroxyvitamin D (25[OH]D), 1,25 dihydroxyvitamin D (1,25[OH]₂D) and parathyroid hormone (PTH)] were performed before and after supplementation.

RESULTS

Serum 25(OH)D levels before treatment were statistically lower in PCOS women than in NOR patients (P<0.05), even after adjustment for BMI, age and AMH level, but not after adjustment for waist circumference measurement. No difference in the serum AMH levels before and after treatment was observed neither in PCOS patients nor in NOR patients. In both groups, 25(OH)D serum levels were not related to serum AMH levels, serum 1,25(OH)₂D and serum PTH levels, before and after treatment.

CONCLUSION

We found no evidence that serum calciotropic hormones are linked to circulating AMH levels, particularly in PCOS.