Women’s vitamin D levels and IVF results: a systematic review of the literature and meta-analysis, considering three categories of vitamin status (replete, insufficient and deficient)

Vitamin D levels in couples undergoing in vitro fertilization treatment: lack of association with embryo quality or pregnancy rates

OBJECTIVE

To investigate the potential impact of vitamin D (VD) serum levels on couples going through in vitro fertilization treatment in terms of embryo quality and pregnancy rates.

DESIGN

A retrospective cohort study.

SETTING

A private human reproduction center.

PATIENT(S)

A total of 267 couples underwent intracytoplasmic sperm injections between January 2017 and March 2019.

INTERVENTION(S)

The couples were categorized into four groups on the basis of 25-hydroxy VD (25OHD) levels measured at the beginning of the stimulation protocol: group 1 with 25OHD levels ≥30 ng/mL for both women and men; group 2 with 25OHD levels <30 ng/mL for both; group 3 women with 25OHD levels <30 ng/mL and men with 25OHD levels ≥30 ng/mL; and group 4 with women with 25OHD level ≥30 ng/mL and men with 25OHD level <30 ng/mL.

MAIN OUTCOME MEASURE(S)

We consider the quantity and quality of embryos during the cleavage as well as blastocyst stages as primary outcomes. Correspondingly, the clinical pregnancy rate (CPR) was regarded as a secondary outcome.

RESULT(S)

Our findings revealed no significant correlations between the studied VD groups and the evaluated outcomes. This includes the quantity and quality of embryos during the cleavage and blastocyst stages, as well as the CPR. Primary analysis revealed a small but statistically significant difference in the duration of controlled ovarian stimulation between group 1 and group 2 (95% confidence interval, 0.07-3.04) and between group 1 and group 3 (95% confidence interval, 0.05-3.23).

CONCLUSION(S)

The present study found no correlation between the studied VD levels and the quantity as well as quality of cleavage or blastocyst stage embryos, nor did it show any impact on CPRs. Further well-designed, prospective studies are warranted to determine whether and how vitamin D affects reproductive outcomes.

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.

Do Popular Diets Impact Fertility?

Infertility affects 15% of the population in developed countries, and its prevalence is increasing. Fertility can be influenced by different factors. Although key factors like maternal age cannot be changed, there is growing evidence that other modifiable factors, such as diet, can have an impact on fertility. Diet has become increasingly important in recent years for a number of reasons: the new trend toward a healthy lifestyle, the higher prevalence of certain digestive disorders, a lack of time that leads people to consume more prepared and processed food, and personal choice to not eat meat, among others. To meet these needs, several diets have recently become popular, such as the Mediterranean diet, known as the gold standard of health; the DASH diet, known for preventing hypertension; the Western diet, characterized by processed food; the ketogenic diet, characterized by low carbohydrate intake; and the vegetarian diet, which is the choice for people who do not eat meat or animal by-products. Diets present a unique composition characterized by the presence or absence of specific nutrients, which have also been associated with male and female fertility individually. This review assesses the impact of these diets and of macro- and micronutrients on both female and male fertility.

Association Between Vitamin D Level and Clinical Outcomes of Assisted Reproductive Treatment: A Systematic Review and Dose-Response Meta-Analysis

The investigation about association between vitamin D level and clinical outcomes of assisted reproductive treatment showed various outcomes. This study aimed to review the correlation between vitamin D and outcomes of assisted reproductive treatment. The search was registered on the PROSPERO database (CRD42023458040). PubMed, Embase, Medline, ClinicalTrials.gov, and Cochrane databases were searched up to July 2023. Twenty-three observational studies were selected for meta-analysis. Comparing groups with deficient and 'insufficient + sufficient' vitamin D level, meta-analysis showed positive correlation between clinical pregnancy rate and vitamin D (OR 0.81, 95%CI: 0.70, 0.95, P = 0.0001). Comparing groups with 'deficient + insufficient' and sufficient vitamin D level, meta-analysis showed positive correlation between vitamin D and clinical pregnancy rate (OR 0.71, 95%CI: 0.55, 0.91, P = 0.006), vitamin D and live birth rate (OR 0.69, 95%CI: 0.54, 0.89, P = 0.003). Subgroup analysis did not show the source of high heterogeneity. No correlation was found in biochemical pregnancy rate, ongoing pregnancy rate, miscarriage rate and implantation rate. In dose-response meta-analysis, a nonlinear association was found between vitamin D levels and outcomes when levels are below approximately 24 ng/L. The study shows that vitamin D level is associated with clinical pregnancy rate and live birth rate. Low vitamin D level does not influence biochemical pregnancy rate, ongoing pregnancy rate, miscarriage rate and implantation rate. Furthermore, 24 ng/L may be a possible threshold of vitamin D concentration in assisted reproduction therapy.

Do serum vitamin D levels affect assisted reproductive outcomes and perinatal outcomes in young non-PCOS patients? A retrospective study

PURPOSE

This study aimed to determine the influence of serum vitamin D levels on assisted reproductive and perinatal outcomes in young non-polycystic ovary syndrome (PCOS) patients.

METHODS

A total of 3397 non-PCOS women under 35 years who underwent their first IVF/ICSI cycle at the Reproductive Medicine Center of the Third Affiliated Hospital of Zhengzhou University, from 2018 to 2019, were included. The women were categorized into two groups based on their serum 25(OH)D concentrations: deficient group [25(OH)D < 50 nmol/L] and non-deficient group [25(OH)D ≥ 50 nmol/L]. Ovulation induction results, clinical pregnancy rate, cumulative live birth rate (CLBR), and perinatal outcomes of both groups were compared.

RESULTS

A total of 1113 non-PCOS women had successful pregnancies in their first completed IVF cycle. Comparison of laboratory results between the two groups revealed a significantly higher number of oocytes retrieved in the vitamin D-non-deficient group (15.2 ± 6.8 vs. 14.5 ± 6.7, p = 0.015). After controlling for confounding factors, there was no significant difference in the CLBR between the vitamin D-deficient group and the non-deficient group (71.0%, 1,973/2,778 vs. 69.0%, 427/619, p = 0.314, unadjusted). The prevalence of gestational diabetes mellitus (GDM) was higher in the vitamin D-deficient group than in the vitamin D-non-deficient group in both fresh-cycle singleton live births (3.8% vs. 1.2%) and twin live births (2.3% vs. 1.5%).

CONCLUSION

This study demonstrated that vitamin D-deficient group had a lower number of oocytes retrieved than the non-deficient group and a higher prevalence of GDM, suggesting that vitamin D deficiency impacts assisted pregnancies and perinatal outcomes in infertile non-PCOS women. However, further studies are required to confirm these findings.

Effect of Stress on Each of the Stages of the IVF Procedure: A Systematic Review

The aim of this systematic review was to examine if chronic or acute stress, measured by questionnaires or physiological biomarkers, has a separate impact on each different stage in the IVF process. A systematic search of peer-reviewed literature was performed in three databases with keywords. Preselection included 46 articles, and in all, 36 articles were included. Most studies concluded that stress has a negative effect on IVF treatment. The egg retrieval time point was most affected by chronic and acute stress. Through this research, there may be an association between chronic stress and the fertilization stage. Only chronic stress impacted the embryo transfer stage and further evidence suggested that stress decreased during this stage. The pregnancy rate stage was weakly associated with stress. Follicular cortisol was found to affect three stages. Chronic and acute stress significantly and negatively affected the egg retrieval time point. Chronic stress was associated with a lesser extent with the fertilization point, and no significant relationship between acute stress and the embryo transfer and pregnancy rate stages were found. Follicular cortisol was found to affect the process. This review contributes to the research of the relationship between stress and IVF success.

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.

Calcifediol in the management of vitamin D deficiency-related skeletal and extraskeletal diseases: overview and clinical cases

As well as being essential for musculoskeletal health, vitamin D is involved in numerous other physiological processes. Poor vitamin D status is linked to a wide range of diseases, including cardiovascular disease, autoimmune conditions, pulmonary disorders and upper respiratory tract infections. While optimal target concentrations of serum 25-hydroxyvitamin D (25(OH)D) for health maintenance or therapeutic purposes are still the subject of debate, there is reasonable agreement that serum 25(OH)D levels <50 nmol/L (20 ng/mL) constitute vitamin D deficiency and that severe deficiency states (serum 25(OH)D levels <25-30 nmol/L ≈ 10-12 ng/mL) should be avoided. Main strategies to maintain or improve vitamin D status are food supplementation and therapeutic use of medicinal forms of vitamin D. In this review, we examine evidence that implicates vitamin D deficiency in diverse conditions in the clinical settings of endocrinology, rheumatology, pneumology and reproductive health. Cholecalciferol (vitamin D3) is the most frequently used vitamin D supplement worldwide, though calcifediol (25-hydroxyvitamin D3) has recently become more widely available. Calcifediol is one step closer than cholecalciferol in the metabolic pathway to biologically active vitamin D. Pharmacokinetic differences between these vitamin D metabolites confer putative advantages for calcifediol in certain clinical situations. The clinical use of calcifediol is explored more closely through case studies, which illustrate its adjunctive role in the treatment of several vitamin D deficiency-related skeletal and extraskeletal diseases.

Season and temperature do not affect cumulative live birth rate and time to live birth in in vitro fertilization

Objective

To explore whether season and temperature on oocyte retrieval day affect the cumulative live birth rate and time to live birth.

Methods

This was a retrospective cohort study. A total of 14420 oocyte retrieval cycles from October 2015 to September 2019. According to the date of oocyte retrieval, the patients were divided into four groups (Spring(n=3634);Summer(n=4414); Autumn(n=3706); Winter(n=2666)). The primary outcome measures were cumulative live birth rate and time to live birth. The secondary outcome measures included the number of oocytes retrieved, number of 2PN, number of available embryos and number of high-quality embryos.

Results

The number of oocytes retrieved was similar among the groups. Other outcomes, including the number of 2PN (P=0.02), number of available embryos (p=0.04), and number of high-quality embryos (p<0.01) were different among the groups. The quality of embryos in summer was relatively poor. There were no differences between the four groups in terms of cumulative live birth rate (P=0.17) or time to live birth (P=0.08). After adjusting for confounding factors by binary logistic regression, temperature (P=0.80), season (P=0.47) and duration of sunshine(P=0.46) had no effect on cumulative live births. Only maternal age (P<0.01) and basal FSH (P<0.01) had an effect on cumulative live births. Cox regression analysis suggested no effect of season(P=0.18) and temperature(P=0.89) on time to live birth. Maternal age did have an effect on time to live birth (P<0.01).

Conclusion

Although season has an effect on the embryo, there was no evidence that season or temperature affect the cumulative live birth rate or time to live birth. It is not necessary to select a specific season when preparing for IVF.

Prevalence of Vitamin D Insufficiency and Its Determinants among Women Undergoing In Vitro Fertilization Treatment for Infertility in Sweden

There is a lack of research on women with infertility in the northern latitudes, where vitamin D insufficiency is high. Therefore, this study aimed to assess the prevalence and determinants of vitamin D insufficiency (serum 25(OH)D concentration < 50 nmol/L) among women undergoing in vitro fertilization (IVF) treatment. Thus, 265 women scheduled for IVF/intracytoplasmic sperm injection (ICSI) between September 2020 and August 2021 at Sahlgrenska University Hospital in Gothenburg, Sweden, were included. Data on serum 25(OH)D concentration, vitamin D intake, and sun exposure were collected via questionnaires and blood samples. Approximately 27% of the women had 25(OH)D insufficiency, which was associated with longer infertility duration. The likelihood of insufficiency was higher among women from non-Nordic European countries (OR 2.92, 95% CI 1.03-8.26, adjusted p = 0.043), the Middle East (OR 9.90, 95% CI 3.32-29.41, adjusted p < 0.001), and Asia (OR 5.49, 95% CI 1.30-23.25, adjusted p = 0.020) than among women from Nordic countries. Women who did not use vitamin D supplements were more likely to have insufficiency compared with supplement users (OR 3.32, 95% CI 1.55-7.10, adjusted p = 0.002), and those who avoided sun exposure had higher odds of insufficiency compared to those who stayed "in the sun all the time" (OR 3.24, 95% CI 1.22-8.62, adjusted p = 0.018). Women with infertility in northern latitudes and those from non-Nordic countries who avoid sun exposure and do not take vitamin supplements have a higher prevalence of 25(OH)D insufficiency and longer infertility duration.

Summer is not associated with higher live birth rates in fresh IVF/ICSI cycles: a population-based nationwide registry study

STUDY QUESTION

Is summer associated with a higher live birth rate after fresh IVF/ICSI?

SUMMARY ANSWER

There was no support for a higher live birth rate after fresh IVF/ICSI when treatment was performed during the summer season.

WHAT IS KNOWN ALREADY

Seasonal variations in human natural conception and birth rates are well described. It has been hypothesized that serum vitamin D, levels of which are associated with sun exposure, may have a role in human natural conception rates. However, the association between seasons and IVF outcomes has not yet been clarified and conflicting reports have been published. Furthermore, it has been suggested that women with normal vitamin D levels have a better pregnancy outcome after ART compared to those with vitamin D insufficiency.

STUDY DESIGN, SIZE, DURATION

A nationwide, register-based cohort study including all first-time fresh IVF/ICSI treatments (n = 52 788) leading to oocyte retrieval in Sweden between 2009 and 2018 was carried out.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All first-time fresh IVF/ICSI cycles leading to oocyte retrieval were identified in the National Quality Registry of Assisted Reproduction. Data collected included patient characteristics as well as information about the treatment cycle and pregnancy outcome. The patients were divided into season subgroups, (summer, autumn, winter and spring) based on the date of oocyte retrieval. The primary outcome was live birth rate, which was defined as the number of live births per oocyte retrieval and embryo transfer (ET). Other outcomes included clinical pregnancy per ET and miscarriage per clinical pregnancy. Logistic regression with multiple imputation was performed to evaluate whether there was an association between season and IVF/ICSI outcomes, with summer as reference. Adjustments were made for woman’s age, year of treatment, BMI, total FSH/hMG dose, type of treatment, fertilization type, embryonic stage at ET and number of embryos transferred.

MAIN RESULTS AND THE ROLE OF CHANCE

Live birth rate per oocyte retrieval ranged between 24% and 26% among seasons. A significantly higher live birth rate was seen for spring compared with summer, 26% versus 24%, respectively (adjusted odds ratio (OR) 1.08, 95% CI 1.02–1.16, P = 0.02). No significant association was seen when winter and autumn were compared with summer. Live birth rate per ET ranged between 29% and 31% among seasons. A significantly higher live birth rate was seen for spring and autumn compared with summer, at 31% and 31%, respectively versus 29% (adjusted OR 1.08, 95% CI 1.01–1.16, P = 0.04 and adjusted OR 1.09, 95% CI 1.01–1.16, P = 0.02), respectively. No significant association was seen when winter was compared with summer. Clinical pregnancy rate varied between 36% and 38% and miscarriage rate between 16% and 18%, with no significant seasonal associations.

LIMITATIONS, REASONS FOR CAUTION

Possible limitations are the retrospective design of the study and unmeasured confounders. Another limitation is that a generalized estimating equation (GEE) model was not used. The use of a GEE model would have made it possible to include all started fresh IVF/ICSI cycles since it allows for correction for any dependence between cycles within women.

WIDER IMPLICATIONS OF THE FINDINGS

The results of this large registry study give no support for the hypothesis that IVF/ICSI treatments performed during summer season, with the highest degree of sunlight and vitamin D synthesis, is associated with higher pregnancy and live birth rates. In fact, our results showed significantly lower live birth rates during summer compared with spring and autumn. However, the magnitude of this difference was small and unlikely of clinical value. We suggest that season should not be taken into consideration when planning and performing fresh IVF/ICSI treatments.

STUDY FUNDING/COMPETING INTEREST(S)

Financial support was received through the Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement (ALFGBG-70 940) and grants from the Hjalmar Svensson’s Research Foundation (HJSV2021019 and HJSV2021037). None of the authors declare any conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Preconception vitamin D intake and obstetric outcomes in women using assisted reproductive technology: the Japan Environment and Children’s Study

Background

In reproductive medicine, vitamin D (VitD) is of particular interest because its deficiency has been linked to various infertility issues. Thus, preconception care, including appropriate VitD supplementation, is essential, especially in women using assisted reproductive technology (ART). Despite the therapeutic benefits of VitD, adverse events due to a high daily intake may influence obstetric outcomes. However, the effects of either low or high preconception VitD intake on obstetric outcomes, including the outcomes in women who used ART, remain unclear. Therefore, the aim of this study was to examine the association between pre-pregnancy daily VitD intake and obstetric outcomes in Japanese women, including those who conceived through ART.

Methods

Data were obtained from the Japan Environment and Children’s study database comprising 92,571 women recruited between January 2011 and March 2014 in Japan. Participants were categorized into five quintiles according to pre-pregnancy VitD intake (Q1 and Q5 had the lowest and highest VitD intake, respectively) and stratified according to the use of ART. Multiple logistic regression was performed to identify the effects of pre-pregnancy VitD intake on preterm birth (PTB), low-birth weight infant (LBW), and small for gestational age (SGA).

Results

Using Q3 (middle VitD intake) as a reference, our analysis revealed that Q5 (highest VitD intake) showed an increased risk of LBW < 1500 g (adjusted odds ratio [aOR]: 1.09, 95% confidence interval [CI]: 1.00–1.18) and SGA (aOR: 1.26, 95% CI: 1.14–1.39) among women who conceived without ART. Among women who conceived with ART, we found that Q5 (highest VitD intake) showed an increased risk of PTB at < 37 weeks (aOR: 2.05, 95% CI: 1.27–3.31).

Conclusion

The present study revealed that higher VitD intake before pregnancy may affect perinatal outcomes, particularly in women using ART. Our findings may facilitate personalized preconceptional counseling regarding VitD intake based on the method of conception, especially among women using ART.

Calcifediol (25OHD) Deficiency and Its Treatment in Women's Health and Fertility

Currently, there is abundant scientific evidence showing that the vitamin D endocrine system (VDES) is a highly complex endocrine system with multiple actions in different regions of the body. The unequivocal presence of vitamin D receptors in different tissues related to fertility, and to specific aspects of women's health such as pregnancy, undoubtedly implies functions of this steroid hormone in both male and female fertility and establishes relationships with different outcomes of human gestation. In order to review the role of the VDES in human fertility, we evaluated the relationships established between 25-hydroxyvitamin D (calcifediol) deficiency and in vitro fertilization, as well as aspects related to ovarian reserve and fertility, and commonly diagnosed endocrinopathies such as polycystic ovary disease. Likewise, we briefly reviewed the relationships between calcifediol deficiency and uterine fibroids, as well as the role that treatment may have in improving human fertility. Finally, the best scientific evidence available on the consequences of calcifediol deficiency during pregnancy is reviewed in relation to those aspects that have accumulated the most scientific literature to date, such as the relationship with the weight of the newborn at the time of delivery, the appearance of preeclampsia, and the risk of developing gestational diabetes and its final consequences for the pregnancy. To date, there is no definitive consensus on the necessary dose for treatment of calcifediol deficiency in the therapeutic management of infertility or during pregnancy. Large prospective clinical intervention studies are needed to clarify the benefits associated with this supplementation and the optimal dose to use in each situation. Although most intervention studies to date have been conducted with cholecalciferol, due to its much longer history of use in daily care, the use of calcifediol to alleviate 25-hydroxyvitamin D deficiency seems safe, even during pregnancy. The unequivocal presence of vitamin D receptors in very different tissues related to human fertility, both male and female, as well as in structures typical of pregnancy, allows us to investigate the crucial role that this steroid hormone has in specific aspects of women's health, such as pregnancy and the ability to conceive. Well-designed clinical studies are needed to elucidate the necessary dose and the best form of treatment to resolve the very common calcifediol deficiency in women of reproductive age.

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.

Proteomics based drug repositioning applied to improve in vitro fertilization implantation: an artificial intelligence model

Embryo implantation is one of the most inefficient steps in assisted reproduction, so the identifying drugs with a potential clinical application to improve it has a strong interest. This work applies artificial intelligence and systems biology-based mathematical modeling strategies to unveil potential treatments by computationally analyzing and integrating available molecular and clinical data from patients. The mathematical models of embryo implantation computationally generated here simulate the molecular networks underneath this biological process. Once generated, these models were analyzed in order to identify potential repositioned drugs (drugs already used for other indications) able to improve embryo implantation by modulating the molecular pathways involved. Interestingly, the repositioning analysis has identified drugs considering two endpoints: (1) drugs able to modulate the activity of proteins whose role in embryo implantation is already bibliographically acknowledged, and (2) drugs that modulate key proteins in embryo implantation previously predicted through a mechanistic analysis of the mathematical models. This second approach increases the scope open for examination and potential novelty of the repositioning strategy. As a result, a list of 23 drug candidates to improve embryo implantation after IVF was identified by the mathematical models. This list includes many of the compounds already tested for this purpose, which reinforces the predictive capacity of our approach, together with novel repositioned candidates (e.g., Infliximab, Polaprezinc, and Amrinone). In conclusion, the present study exploits existing molecular and clinical information to offer new hypotheses regarding molecular mechanisms in embryo implantation and therapeutic candidates to improve it. This information will be very useful to guide future research.Abbreviations: IVF: in vitro fertilization; EI: Embryo implantation; TPMS: Therapeutic Performance Mapping System; MM: mathematical models; ANN: Artificial Neuronal Networks; TNFα: tumour necrosis factor factor-alpha; HSPs: heat shock proteins; VEGF: vascular endothelial growth factor; PPARA: peroxisome proliferator activated receptor-α PXR: pregnane X receptor; TTR: transthyretin; BED: Biological Effectors Database; MLP: multilayer perceptron.