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

Effect of vitamin D supplementation on frozen embryo transfer cycle outcomes

The role of serum 25-OH D3 (D3) in the physiology and regulation of the female genital system has gained significant research interest. Recent data have suggested that sufficient D3 levels are associated with improved outcomes of in vitro fertilization (IVF), although other studies failed to confirm so. Screening for D3 levels before IVF is becoming common practice in many IVF centres, and D3 insufficiency is treated with supplements before treatment. However, little is known about the effect of this intervention on D3 levels during endometrial preparation for frozen-embryo transfer (FET) cycles, especially regarding clinical outcomes. To examine the effect of vitamin D supplementation and the impact of vitamin D status in women undergoing FET cycles, a prospective study of infertile women undergoing FET cycles was carried out. Initial screening of D3 levels was performed in 252 infertile women before a FET cycle, and where insufficiency was found (<30 ng/mL) [115 (45.6%)], supplements were prescribed according to a standardized protocol. Serum D3 levels were measured at three distinct time-points: at the initiation of endometrial preparation (T1), embryo transfer (T2), and beta-hCG testing (T3). We found no significant difference in ongoing pregnancy [40 (34.8%) vs. 51 (37.2%); odds ratio (OR) 0.90, 95% confidence interval (CI) 0.54-1.51; adjusted OR 1.04, 95% CI 0.58-1.83], live birth, positive β-hCG, clinical pregnancy, miscarriage, and ectopic pregnancy rates between D3-insufficient participants at T1 receiving vitamin D and D3-replete ones not receiving any supplementation (p-values >0.05). We also found no significant difference in ongoing pregnancy [21 (30.9%) vs. 66 (40.2%), and 17 (34.0%) vs. 51 (41.5%)] and the rest of the outcomes between D3-insufficient and replete participants at T2 and T3, respectively (p-values >0.05). In conclusion, this prospective cohort study of women undergoing FET cycles found no significant difference in ongoing pregnancy rates between D3-insufficient participants receiving supplementation at the beginning of endometrial preparation and replete ones receiving no supplementation. Large, high-quality trials are required to further investigate this hypothesis and compare the IVF outcomes between replete participants, insufficient participants receiving no supplementation, and insufficient participants receiving supplementation.

Vitamin D in Reproductive Health Disorders: A Narrative Review Focusing on Infertility, Endometriosis, and Polycystic Ovarian Syndrome

Vitamin D (VD) is a fat-soluble steroid hormone with essential physiological functions beyond calcium and bone metabolism. In recent years, its role in women's reproductive health has gained attention, influencing ovarian function, follicular development, endometrial receptivity, and steroid hormone regulation. VD deficiency has been linked to reproductive disorders such as polycystic ovarian syndrome (PCOS), endometriosis, and infertility. Studies indicate that up to 40-50% of healthy pregnant women have insufficient VD levels, which may contribute to adverse pregnancy outcomes and reduced fertility. With growing evidence connecting VD to reproductive health, this review examines its molecular and endocrine mechanisms in fertility, endometriosis, and PCOS. It explores VD's therapeutic potential and its implications for improving clinical approaches and future research in reproductive medicine. Maintaining adequate VD levels is crucial for ovarian function, immune modulation in reproductive tissues, and overall fertility. Its deficiency is associated with insulin resistance, hormonal imbalances, and inflammatory processes, which contribute to reproductive pathophysiology. Establishing reference values for VD in reproductive medicine is essential for optimizing fertility treatments and improving clinical outcomes. This review synthesizes current research on VD's role in reproductive health and highlights the need for further investigation into its therapeutic applications.

Effect of pre-conception serum vitamin D level on pregnancy outcomes in women undergoing in vitro fertilization with fresh embryo transfer: a retrospective analysis

BACKGROUND

This study aims to investigate the association of pre-conception vitamin D levels on adverse pregnancy outcomes in women undergoing in vitro fertilization with fresh embryo transfer.

METHODS

This was a retrospective cohort study using archived serum 25-hydroxyvitamin D measured in the pre-conception period before ovarian stimulation in patients undergoing in vitro fertilization with fresh autologous embryo transfer. A total of 306 women were included and adverse pregnancy outcomes in their resulting pregnancy were recorded. Patients who were vitamin D deficient (< 20ng/ml) were compared with those who were non-deficient (≥20ng/ml) and analysed for any association with adverse pregnancy outcomes.

RESULTS

A total of 16/306 (5.3%) patients had hypertensive disorders of pregnancy (gestational hypertension and/or pre-eclampsia). The adjusted odds ratio for hypertensive disorders of pregnancy using vitamin D deficiency as a reference was 0.190 (95% CI 0.042-0.852) (p = 0.030). Other pregnancy complications were not significantly different with regards to pre-conception vitamin D status.

CONCLUSIONS

Pre-conception vitamin D deficiency is associated with an increased risk of hypertensive disorders in pregnancy in women undergoing in vitro fertilization with fresh embryo transfer.

TRIAL REGISTRATION

HKUCTR 2361 (9th March 2018).

The association between Vitamin D deficiency and clinical pregnancy rate in IVF patients with different age

Background

The aim of the present study was to investigate the impact of serum VD status on IVF outcomes and to observe the effect of VD deficiency on the expression of the endometrial receptivity marker HOXA10.

Materials and methods

Patients undergoing their first IVF cycles were divided into 3 groups according to VD levels (deficient: <20 ng/mL, insufficient: 20-29.9 ng/mL), and replete ≥30 ng/mL). IVF laboratory parameters, implantation rate, and clinical pregnancy rate were compared among these groups according to patient age (≥ 35 years old and < 35 years old). In addition, the expression of HOXA10 was analyzed using quantitative RT-PCR (qRT-PCR) and western blot in mRNA and protein levels, respectively.

Results

A total of 1459 patients were included. Clinical pregnancy outcomes were significantly worse in vitamin D-deficient patients of advanced age than in other patients. VD status was a predictor of clinical pregnancy according to the multivariate regression model (Deficient: OR = 0.74, 95% CI: 0.59-0.90, P = 0.022; Insufficient: OR = 0.85, 95% CI: 0.70-1.10, P = 0.104; Reference = Replete). However, clinical pregnancy outcomes were comparable among the three groups of young patients. Endometrial tissue was collected from a total of 35 women. HOXA10 expression was significantly lower only in young women in the vitamin D deficiency group. Furthermore, among patients of advanced age, HOXA10 levels were significantly decreased in both vitamin D-deficient and vitamin D-insufficient women.

Conclusion

VD deficiency appears to lead to poorer clinical pregnancy outcomes in patients of advanced age. In the future we can observe whether pregnancy outcomes can be improved in such patients with vitamin D supplementation. In addition, a possible explanation for the worse results may be the detrimental effect of reduced HOXA10 expression on endometrial receptivity.

Effects of preconceptional vitamin D levels on in vitro fertilization outcomes in infertile patients with polycystic ovary syndrome: A retrospective cohort study

BACKGROUND

Vitamin D plays various roles in different stages of reproduction, and abnormalities in its levels are associated with diseases such as polycystic ovary syndrome (PCOS). This study aimed to determine the relationship between initial vitamin D levels and in vitro fertilization (IVF) outcomes in PCOS patients.

METHODS

This retrospective cohort study included 1174 PCOS patients who consulted the Acıbadem Maslak Hospital IVF Clinic between January 2015 and March 2021. We investigated the effect of preconceptional vitamin D levels on IVF outcomes using data analysis with SigmaPlot 14.5.

RESULTS

We found a significant positive correlation between preconceptional vitamin D levels and positive clinical pregnancy rates (p < 0.001) as well as increased endometrial thickness (EMT) on human chorionic gonadotropin (hCG) day (p < 0.001, r = 0.262). The optimal vitamin D cut-off value for predicting positive hCG test results was identified as 13.24 ng/mL, as determined by receiver operating characteristic curve analysis (sensitivity = 0.839, specificity = 0.677). No association was observed with other IVF outcome parameters, miscarriage rates, or clinical pregnancy rates based on EMT.

CONCLUSIONS

The study suggests that PCOS patients with vitamin D levels above 13.24 ng/mL are more likely to achieve positive hCG results after IVF. These findings highlight the potential importance of vitamin D supplementation in improving pregnancy outcomes for PCOS patients. Additionally, increased EMT on hCG day may explain the higher clinical pregnancy rates associated with elevated vitamin D levels.

The Key Role of Vitamin D in Female Reproductive Health: A Narrative Review

Vitamin D, besides its crucial role in bone health and immune function, has received increased attention in recent years due to its possible impact on many processes related to female reproductive health. Recent research has tried to explain the role played by vitamin D in maintaining adequate hormonal status, fertility, and pregnancy outcomes. Our aim for this narrative literature review was to highlight and explain the mechanisms through which vitamin D status impacts female reproductive health. We believe this represents a very important subject of research, especially due to the increased incidence of infertility nowadays. Further studies are necessary on the association between vitamin D status and female reproductive health in order to fully understand its effects and to reach a consensus regarding vitamin D supplementation as a method to improve fertility status.

Supplementation with vitamin D improves the embryo quality in in vitro fertilization (IVF) programs, independently of the patients' basal vitamin D status

PURPOSE

The study aims to demonstrate the effects of Vitamin D (VD) supplementation, prior to oocyte pick-up within IVF protocols, in women with diverse VD status at the enrollment.

METHODS

A total of 204 women eligible for intra-cytoplasmatic sperm injection (ICSI) cycles were included in the study and two homogeneous groups were selected from the database. Both group of patients with normal VD baseline level (> 40 ng/ml) and patients with low VD baseline level (< 20 ng/ml) were divided into control group and treatment group. The control group followed the standard procedure. The treatment group was supplemented with vitamin D3 as cholecalciferol in combination with Myo-Inositol, folic acid, and melatonin 3 months before standard procedure, once a day in the evening.

RESULTS

VD levels significantly increased in the study group of low baseline VD, both in serum and in the follicular fluid compared to controls. The treatment induced a significant improvement of the embryo quality in both group of patients considered.

CONCLUSION

Supplementation of VD in patients undergoing ICSI procedures significantly improved the number of top-quality embryos compared with the control group, either starting from VD normal baseline values or starting from low values.

TRIAL REGISTRATION NUMBER

07/2018.

No evidence of a causal relationship between miscarriage and 25-hydroxyvitamin D: a Mendelian randomization study

STUDY QUESTION

Is there a causal relationship between 25-hydroxyvitamin D (25OHD) and miscarriage?

SUMMARY ANSWER

In this study, little evidence of a causal relationship was found between low serum 25OHD concentration or vitamin D deficiency and the risk of miscarriages.

WHAT IS KNOWN ALREADY

Associations between low vitamin D levels and increased risk of miscarriage have been reported, but causality is unclear.

STUDY DESIGN SIZE DURATION

The latest and largest genome-wide association studies (GWAS) for serum 25OHD concentration (n = 417 580), vitamin D deficiency (426 cases and 354 812 controls), miscarriage (16 906 cases and 149 622 controls), and the number of miscarriages (n = 78 700) were used to explore the causal association between serum vitamin D levels and miscarriage by two-sample Mendelian randomization analysis.

PARTICIPANTS/MATERIALS SETTING METHODS

This study was based on summary GWAS results from the FinnGen database and the UK Biobank. The random-effect inverse-variance weighted method was regarded as the primary analysis; MR-Egger, weighted median, weighted mode, simple mode, and MR-pleiotropy residual sum and outlier (MR-PRESSO) were further employed as complementary methods. MR-Egger intercept analysis and MR-PRESSO were employed to test pleiotropy, and Cochran's Q statistic and leave-one-out sensitivity analysis were used to determine the heterogeneity and robustness of the overall estimates, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

There was insufficient evidence of causal associations between serum 25OHD concentration and miscarriage (odds ratio (OR) = 0.995, 95% CI: 0.888 to 1.114, P = 0.927), or the number of miscarriages (β = -0.004, 95% CI: -0.040 to 0.032, P = 0.829). Furthermore, little evidence of causality between genetically determined vitamin D deficiency to miscarriage (OR = 0.993, 95% CI: 0.966 to 1.021, P = 0.624), or the number of miscarriages (β = 0.001, 95% CI: -0.009 to 0.011, P = 0.828), was observed. The results of the sensitivity analysis were robust, and no significant heterogeneity or horizontal pleiotropy was found.

LIMITATIONS REASONS FOR CAUTION

This study is limited by the absence of female-specific GWAS data and the limited amount of GWAS data available for this study, as well as the need for caution in generalizing the findings to non-European ethnic groups.

WIDER IMPLICATIONS OF THE FINDINGS

These findings enhance the current understanding of the intricate association between vitamin D and pregnancy outcomes, challenging prevailing beliefs regarding the strong association with miscarriage. The results provide a special perspective that may prompt further exploration and potentially offer insights for guiding future research and informing clinical guidelines pertaining to the management of miscarriage.

STUDY FUNDING/COMPETING INTERESTS

This project was supported by the Hubei Provincial Natural Science Foundation Program General Surface Project (2022CFB200), the Key Research & Developmental Program of of Hubei Province (2022BCA042), the Fundamental Research Funds for the Central Universities (2042022gf0007, 2042022kf1210), and the Interdisciplinary Innovative Talents Foundation from Renmin Hospital of Wuhan University (JCRCWL-2022-001, JCRCYG-2022-009). All authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Beyond the Umbrella: A Systematic Review of the Interventions for the Prevention of and Reduction in the Incidence and Severity of Ovarian Hyperstimulation Syndrome in Patients Who Undergo In Vitro Fertilization Treatments

Ovarian hyperstimulation syndrome (OHSS) is the main severe complication of ovarian stimulation for in vitro fertilization (IVF) cycles. The aim of the current study was to identify the interventions for the prevention of and reduction in the incidence and severity of OHSS in patients who undergo IVF not included in systematic reviews with meta-analyses of randomized controlled trials (RCTs) and assess and grade their efficacy and evidence base. The best available evidence for each specific intervention was identified, analyzed in terms of safety/efficacy ratio and risk of bias, and graded using the Oxford Centre for Evidence-Based Medicine (CEBM) hierarchy of evidence. A total of 15 interventions to prevent OHSS were included in the final analysis. In the IVF population not at a high risk for OHSS, follitropin delta for ovarian stimulation may reduce the incidence of early OHSS and/or preventive interventions for early OHSS. In high-risk patients, inositol pretreatment, ovulation triggering with low doses of urinary hCG, and the luteal phase administration of a GnRH antagonist may reduce OHSS risk. In conclusion, even if not supported by systematic reviews with homogeneity of the RCTs, several treatments/strategies to reduce the incidence and severity of OHSS have been shown to be promising.

The role of serum vitamin D in patients with normal ovarian reserve undergoing the first IVF/ICSI cycle

Background

The debate over the impact of vitamin D in assisted reproduction continues. The purpose of our study was to assess embryo quality and pregnancy outcomes among groups with different levels of vitamin D after the first in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycle in patients with normal ovarian reserve (NOR).

Methods

Patients in this retrospective cohort study were divided into three groups: severe vitamin D deficiency group (25OH-D < 10 ng/ml), vitamin D deficiency group (10 ng/ml ≤ 25OH-D < 20 ng/ml), and non-vitamin D deficiency group (25OH-D ≥ 20 ng/ml). The primary outcome was clinical pregnancy, while the secondary outcomes were mature oocytes, oocyte fertilization, available cleavage embryos, available blastocysts, biochemical pregnancy, early abortion, and embryo implantation. A modified Poisson regression model and multiple linear regression analysis were conducted for the multivariate analysis.

Results

264 NOR patients undergoing the first IVF/ICSI cycles were included. For the primary outcome, there was no significant difference in clinical pregnancy between the severe vitamin D deficiency group and the other two groups (vitamin D deficiency group: adjusted RR = 1.026; 0.780 - 1.350; P = 0.854; non-vitamin D deficiency group: adjusted RR = 1.092; 0.743 - 1.605; P = 0.652). For all secondary outcomes, no significant differences were observed among the severe vitamin D deficiency, vitamin D deficiency, and non-vitamin D deficiency groups (P > 0.05). Exploratory subgroup analyses concerning the season of embryo transfer, phase of embryo transferred, and endometrial thickness, as well as the sensitivity analysis using logistic regression models for the primary outcome, revealed comparable clinical pregnancy rates among the groups (P > 0.05). Subgroup analysis concerning ovarian stimulation protocol indicated that in the subgroup of gonadotrophin-releasing hormone (GnRH) antagonist protocol, the clinical pregnancy rate of the non-vitamin D deficiency group was significantly higher than that of the other two groups (P < 0.05).

Conclusion

Serum vitamin D level was not associated with embryo quality and pregnancy outcomes for patients with NOR. Further studies with greater sample sizes and a longer follow-up period are needed to elucidate the relationships between vitamin D levels and IVF outcomes.

Vitamin D and infertility

PURPOSE OF REVIEW

Vitamin D deficiency has been implicated as a contributing factor to a spectrum of reproductive health burden, including difficulty conceiving, pathogenesis of gynaecological disorders such as uterine fibroids and endometriosis, to metabolic and endocrine burden of polycystic ovarian syndrome (PCOS).

RECENT FINDINGS

There have been recent publications showing that in infertile women who are supplemented with vitamin D, there are higher pregnancy rates; there are improved ovarian reserve parameters in women with diminished ovarian reserve; curtailed fibroid growth in those with uterine myomas; lessened dysmenorrhea in endometriosis patients; and improved menstrual regularity, lowered testosterone, AMH and insulin levels in women with PCOS. In infertile men, sperm parameters, especially motility, are positively correlated with vitamin D serum levels.

SUMMARY

Vitamin D status appears to be relevant to reproductive physiology, and to physiological processes underlying common gynaecological disorders as well as for reproductive success.

The effect of calcitriol on the development and implantation capacity of embryos from hyper-stimulated mice

The evidence concerning the role of vitamin D (VD) in reproduction is still inconclusive. Calcitriol was given to superovulated female mice at the time of FSH injection (Group A), or at day 0.5 of pregnancy (Group B). The retrieved and cultured embryos were transferred to the uteri of pseudopregnant females. Ten animals from each group conceived naturally, and at day 7.5 of pregnancy, the implantation sites were counted. Serum hormone concentrations were determined by ELISA. The expression of CD70, PD-L1, OX-40L, and PIBF on extracellular vesicles (EVs) was tested by flow cytometry. Calcitriol treatment did not alter serum oestradiol concentrations, while 25(OH) D levels significantly decreased in both treated groups. Progesterone concentrations were significantly higher in group A and lower in group B than in the controls. On EVs produced by group B embryos PIBF, CD70, and OX-40L expression were significantly lower, while that of PD-L1 was significantly higher than that of controls. Calcitriol treatment decreased the fertilization rate in group A, and the blastulation rate of cultured embryos in group B, while the implantation capacity of the embryos was not affected, suggesting that depending on the time of administration, VD has an adverse effect on oocyte maturation and embryo development, but not on the implantation rates.