Vitamin D InsufficiencyVitD in FETNCT07681115
An Investigation of the Effect of Vitamin D Level During Frozen Embryo Transfer (FET) in IVF and Pregnancy Outcomes
An observational study of Vitamin D Insufficiency and In Vitro Fertilization and Embryo Transfer, run by Fakih IVF Fertility Center at 1 site in United Arab Emirates.
Trial summary
Vitamin D is best known for keeping our bones healthy, but growing research suggests it may also play a role in fertility. Many In vitro fertilization (IVF) clinics now routinely check vitamin D levels and prescribe supplements before treatment, but the science is still unclear on whether this actually improves the… Read more about this study
- Who is it for?
- Ages 18 to 40 years, women only
- Conditions the study is for
- Vitamin D Insufficiency, In Vitro Fertilization and Embryo Transfer
- How many people
- 126 participants
- Where
- 1 siteUnited Arab Emirates
- Study dates
- 1 Jun 2026to Aug 2027
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 40 years
- Women only
- No healthy volunteers
- Adult
Study population: Women undergoing FET cycle who do not suffer from conditions affecting implantation and have got vitamin D levels tested 3 - 6 months before FET cycle.
Who may be able to join
- Women undergoing frozen embryo transfer (FET) at Fakih IVF.
- Age between 18 and 40 years.
- Body mass index (BMI) between 18 and 40 kg/m².
- Patients who had serum vitamin D levels assessed within three months prior to FET
- Supplementation with Vitamin D if deficient < 30 ng/mL (75 nmol/L).
Who cannot join
- Age below 18 years or above 40 years.
- BMI below 18 kg/m² or above 40 kg/m².
- Patients who did not have vitamin D levels measured within three months prior to FET.
- Patients who were found to have low vitamin D levels but did not receive supplementation.
- Patients with recurrent implantation failure (RIF).
- Patients with known uterine factors affecting implantation (e.g., congenital uterine anomalies, intrauterine adhesions, submucosal fibroids).
- Patients with significant medical comorbidities that may affect pregnancy outcomes.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United Arab Emirates1 site, 1 recruiting
- Recruiting
Fakih IVF Fertility Centre LLC
Abu Dhabi
Dr. Lamiya Mohiyiddeen, MD, FRCOG, +971543676002, lamiya.mohiyiddeen@fakihivf.com
Fatma Bathawab, PhD, +971585707393, fatma.bathawab@fakihivf.com
About this study
Official title: Vitamin D Levels and Pregnancy Outcomes Following Frozen Embryo Transfer (FET) in the UAE
Vitamin D is best known for keeping our bones healthy, but growing research suggests it may also play a role in fertility. Many In vitro fertilization (IVF) clinics now routinely check vitamin D levels and prescribe supplements before treatment, but the science is still unclear on whether this actually improves the chances of pregnancy.
Our study, based in the United Arab Emirates (UAE), aims to find out whether a woman's vitamin D level on the day of her frozen embryo transfer (FET) makes a difference to whether she becomes pregnant and delivers a baby. The UAE is an ideal setting for this research, as vitamin D deficiency is particularly common in the region. The findings could shape how fertility clinics screen and treat women seeking fertility treatment in the future.
Read the detailed description
Serum vitamin D3 has attracted growing research interest for its potential role in female reproductive physiology. While some studies associate sufficient vitamin D3 levels with improved IVF outcomes, others have failed to confirm this, leaving the evidence base contested. Despite this uncertainty, pre-In vitro fertilization (IVF) vitamin D screening and supplementation of insufficient patients has become widespread clinical practice. Evidence specific to frozen embryo transfer (FET) cycles remains particularly limited. Recent prospective studies found no significant difference in ongoing pregnancy, live birth, or implantation rates between vitamin D3-insufficient women receiving supplementation and vitamin D3-replete women who did not, underscoring the need for higher-quality, targeted research. While emerging data support a role for vitamin D in endometrial receptivity, it remains unclear whether correcting insufficiency prior to FET meaningfully improves reproductive success.
To address these gaps, our study will evaluate the association between serum vitamin D3 levels on the day of FET and subsequent pregnancy and delivery outcomes at a UAE fertility center. Supplementation history and relevant clinical variables will be captured via patient questionnaire. Vitamin D status will be classified per International Society of Endocrinology guidance: deficient (<20 ng/mL), insufficient (20-29 ng/mL), and sufficient (≥30 ng/mL). Given the high regional prevalence of vitamin D deficiency, this study is well-positioned to determine whether vitamin D status represents a modifiable determinant of reproductive success, with direct implications for clinical screening and management protocols in this population.
- Being tested
- No Intervention: Observational Cohort
- Keywords
- frozen embryo transfer cycle, Vitamin D
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
No Intervention: Observational CohortOther
There are no interventions in this study. This is an observational cohort study.
| Study group | Role | What they receive |
|---|---|---|
| Women undergoing frozen embryo transfer (FET) at Fakih IVF | The study will enroll women aged 18-40 years with a BMI of 18-40 kg/m² undergoing FET at Fakih IVF, who had serum vitamin D assessed within three months prior to transfer. Women with deficient levels (<30 ng/mL) must have received supplementation prior to FET to be eligible.
Exclusions are designed to reduce confounding: women are excluded if vitamin D was not measured within the required window, if identified deficiency went untreated, or if they have a history of recurrent implantation failure (RIF). Women with uterine factors known to impair implantation including congenital anomalies, intrauterine adhesions, or submucosal fibroids are also excluded, as are those with significant medical comorbidities that may independently affect pregnancy outcomes. Receives: Other: No Intervention: Observational Cohort |
What is being measured
The primary outcome is the main question the study is designed to answer.
Concentration of serum 25-hydroxyvitamin D levels measured on the day of FET
Measured: Vitamin D level tested on the day of FET.
Clinical pregnancy test
Measured: From enrollment on day of FET to 1 month post FET
Secondary outcomes (1)
Live birth rate, miscarriage rate, and preterm birth rate.
Measured: From enrollment to six weeks post partum
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Jul 2026
- Study start1 Jun 2026
- Primary completionJun 2027 (estimated)
- Study completionAug 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (7)Papers the sponsor has linked to this study.
- Other trials for Vitamin D InsufficiencyStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 126 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Fakih IVF Fertility Center
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Lamiya Mohiyiddeen, MD, FRCOG, Principal investigator, Fakih IVF Abu DhabiMichael Fakih, MD, Principal investigator, Fakih IVF Abu Dhabi
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07681115
- Sponsor's protocol ID
- FAKIHIVF-2025-5
- Other IDs
- DOH/ADHRTC/2025/1884
- Acronym
- VitD in FET
- Status last verified
- Jul 2026
- First submitted
- 26 Jun 2026
- Last updated
- 15 Jul 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Not an NIH project
Publications
Chu J, Gallos I, Tobias A, Tan B, Eapen A, Coomarasamy A. Vitamin D and assisted reproductive treatment outcome: a systematic review and meta-analysis. Hum Reprod. 2018 Jan 1;33(1):65-80. doi: 10.1093/humrep/dex326.
PubMed 29149263Anifandis, G., Dafopoulos, K., Messini, C. I., et al. (2021). The impact of vitamin D supplementation on reproductive outcomes in infertile women: A systematic review and meta-analysis. Hormones (Athens), 20(2), 145-154. https://doi.org/10.1007/s42000-021-00291-1
Lerchbaum E, Obermayer-Pietsch B. Vitamin D and fertility: a systematic review. Eur J Endocrinol. 2012 May;166(5):765-78. doi: 10.1530/EJE-11-0984. Epub 2012 Jan 24.
PubMed 22275473Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad MH, Weaver CM; Endocrine Society. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011 Jul;96(7):1911-30. doi: 10.1210/jc.2011-0385. Epub 2011 Jun 6.
PubMed 21646368Wang K, Dong F, Ma S, Bu Z. The association between Vitamin D deficiency and clinical pregnancy rate in IVF patients with different age. Front Endocrinol (Lausanne). 2025 Jan 3;15:1485238. doi: 10.3389/fendo.2024.1485238. eCollection 2024.
PubMed 39829955Hu KL, Gan K, Wang R, Li W, Wu Q, Zheng B, Zou L, Zhang S, Liu Y, Wu Y, Chen R, Cao W, Yang S, Liu FT, Tian L, Zeng H, Xu H, Qiu S, Yang L, Chen X, Pan X, Wu X, Mol BW, Li R, Zhang D. Vitamin D supplementation prior to in vitro fertilisation in women with polycystic ovary syndrome: a protocol of a multicentre randomised, double-blind, placebo-controlled clinical trial. BMJ Open. 2020 Dec 8;10(12):e041409. doi: 10.1136/bmjopen-2020-041409.
PubMed 33293396Christoforidis N, Papapanou M, Michalakis D, Dimitraki M, Chatziparasidou A, Siristatidis C. Effect of vitamin D supplementation on frozen embryo transfer cycle outcomes. Hum Fertil (Camb). 2025 Dec;28(1):2493251. doi: 10.1080/14647273.2025.2493251. Epub 2025 Apr 25.
PubMed 40277196
Study at a glance
From the registry record, last updated by the sponsor on 15 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Vitamin D Levels and Pregnancy Outcomes Following Frozen Embryo Transfer (FET) in the UAE
- ClinicalTrials.gov ID
- NCT07681115
- Acronym / sponsor ID
- VitD in FET / FAKIHIVF-2025-5
- Keywords
- frozen embryo transfer cycle, Vitamin D
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 126 participants (estimated)
- Lead sponsor
- Fakih IVF Fertility CenterUniversity, hospital or other
- Study start
- 1 Jun 2026 (actual)
- Primary completion
- Jun 2027 (estimated)
- Study completion
- Aug 2027 (estimated)
- First posted
- 2 Jul 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Vitamin D is best known for keeping our bones healthy, but growing research suggests it may also play a role in fertility. Many In vitro fertilization (IVF) clinics now routinely check vitamin D levels and prescribe supplements before treatment, but the science is still unclear on whether this actually improves the chances of pregnancy.
Our study, based in the United Arab Emirates (UAE), aims to find out whether a woman's vitamin D level on the day of her frozen embryo transfer (FET) makes a difference to whether she becomes pregnant and delivers a baby. The UAE is an ideal setting for this research, as vitamin D deficiency is particularly common in the region. The findings could shape how fertility clinics screen and treat women seeking fertility treatment in the future.
Detailed description
Serum vitamin D3 has attracted growing research interest for its potential role in female reproductive physiology. While some studies associate sufficient vitamin D3 levels with improved IVF outcomes, others have failed to confirm this, leaving the evidence base contested. Despite this uncertainty, pre-In vitro fertilization (IVF) vitamin D screening and supplementation of insufficient patients has become widespread clinical practice. Evidence specific to frozen embryo transfer (FET) cycles remains particularly limited. Recent prospective studies found no significant difference in ongoing pregnancy, live birth, or implantation rates between vitamin D3-insufficient women receiving supplementation and vitamin D3-replete women who did not, underscoring the need for higher-quality, targeted research. While emerging data support a role for vitamin D in endometrial receptivity, it remains unclear whether correcting insufficiency prior to FET meaningfully improves reproductive success.
To address these gaps, our study will evaluate the association between serum vitamin D3 levels on the day of FET and subsequent pregnancy and delivery outcomes at a UAE fertility center. Supplementation history and relevant clinical variables will be captured via patient questionnaire. Vitamin D status will be classified per International Society of Endocrinology guidance: deficient (<20 ng/mL), insufficient (20-29 ng/mL), and sufficient (≥30 ng/mL). Given the high regional prevalence of vitamin D deficiency, this study is well-positioned to determine whether vitamin D status represents a modifiable determinant of reproductive success, with direct implications for clinical screening and management protocols in this population.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Women undergoing frozen embryo transfer (FET) at Fakih IVF | – | Other: No Intervention: Observational CohortThe study will enroll women aged 18-40 years with a BMI of 18-40 kg/m² undergoing FET at Fakih IVF, who had serum vitamin D assessed within three months prior to transfer. Women with deficient levels (<30 ng/mL) must have received supplementation prior to FET to be eligible. Exclusions are designed to reduce confounding: women are excluded if vitamin D was not measured within the required window, if identified deficiency went untreated, or if they have a history of recurrent implantation failure (RIF). Women with uterine factors known to impair implantation including congenital anomalies, intrauterine adhesions, or submucosal fibroids are also excluded, as are those with significant medical comorbidities that may independently affect pregnancy outcomes. |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult
- Study population
- Women undergoing FET cycle who do not suffer from conditions affecting implantation and have got vitamin D levels tested 3 - 6 months before FET cycle.
Key inclusion criteria (5 listed)
- Women undergoing frozen embryo transfer (FET) at Fakih IVF.
- Age between 18 and 40 years.
- Body mass index (BMI) between 18 and 40 kg/m².
- Patients who had serum vitamin D levels assessed within three months prior to FET
- Supplementation with Vitamin D if deficient < 30 ng/mL (75 nmol/L).
Key exclusion criteria (7 listed)
- Age below 18 years or above 40 years.
- BMI below 18 kg/m² or above 40 kg/m².
- Patients who did not have vitamin D levels measured within three months prior to FET.
- Patients who were found to have low vitamin D levels but did not receive supplementation.
- Patients with recurrent implantation failure (RIF).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| No Intervention: Observational CohortThere are no interventions in this study. This is an observational cohort study. | Other | Women undergoing frozen embryo transfer (FET) at Fakih IVF |
Primary outcome
Concentration of serum 25-hydroxyvitamin D levels measured on the day of FET
Time frame: Vitamin D level tested on the day of FET.
Clinical pregnancy test
Time frame: From enrollment on day of FET to 1 month post FET
1 secondary outcome
Live birth rate, miscarriage rate, and preterm birth rate.
Time frame: From enrollment to six weeks post partum
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 Jul 2026.
- Background: PubMed 29149263Chu J, Gallos I, Tobias A, Tan B, Eapen A, Coomarasamy A. Vitamin D and assisted reproductive treatment outcome: a systematic review and meta-analysis. Hum Reprod. 2018 Jan 1;33(1):65-80. doi: 10.1093/humrep/dex326.
- BackgroundAnifandis, G., Dafopoulos, K., Messini, C. I., et al. (2021). The impact of vitamin D supplementation on reproductive outcomes in infertile women: A systematic review and meta-analysis. Hormones (Athens), 20(2), 145-154. https://doi.org/10.1007/s42000-021-00291-1
- Background: PubMed 22275473Lerchbaum E, Obermayer-Pietsch B. Vitamin D and fertility: a systematic review. Eur J Endocrinol. 2012 May;166(5):765-78. doi: 10.1530/EJE-11-0984. Epub 2012 Jan 24.
- Background: PubMed 21646368Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad MH, Weaver CM; Endocrine Society. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011 Jul;96(7):1911-30. doi: 10.1210/jc.2011-0385. Epub 2011 Jun 6.
- Background: PubMed 39829955Wang K, Dong F, Ma S, Bu Z. The association between Vitamin D deficiency and clinical pregnancy rate in IVF patients with different age. Front Endocrinol (Lausanne). 2025 Jan 3;15:1485238. doi: 10.3389/fendo.2024.1485238. eCollection 2024.
- Background: PubMed 33293396Hu KL, Gan K, Wang R, Li W, Wu Q, Zheng B, Zou L, Zhang S, Liu Y, Wu Y, Chen R, Cao W, Yang S, Liu FT, Tian L, Zeng H, Xu H, Qiu S, Yang L, Chen X, Pan X, Wu X, Mol BW, Li R, Zhang D. Vitamin D supplementation prior to in vitro fertilisation in women with polycystic ovary syndrome: a protocol of a multicentre randomised, double-blind, placebo-controlled clinical trial. BMJ Open. 2020 Dec 8;10(12):e041409. doi: 10.1136/bmjopen-2020-041409.
- Background: PubMed 40277196Christoforidis N, Papapanou M, Michalakis D, Dimitraki M, Chatziparasidou A, Siristatidis C. Effect of vitamin D supplementation on frozen embryo transfer cycle outcomes. Hum Fertil (Camb). 2025 Dec;28(1):2493251. doi: 10.1080/14647273.2025.2493251. Epub 2025 Apr 25.
- Individual participant dataSharing planned: No. Not an NIH project
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Lamiya Mohiyiddeen, MD, FRCOG principal investigator
Fakih IVF Abu Dhabi
Michael Fakih, MD principal investigator
Fakih IVF Abu Dhabi
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Vitamin D Insufficiency and In Vitro Fertilization and Embryo Transfer, run by Fakih IVF Fertility Center at 1 site in United Arab Emirates.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 15 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Arab Emirates. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Dr. Lamiya Mohiyiddeen, MD, FRCOG (+971543676002, lamiya.mohiyiddeen@fakihivf.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Concentration of serum 25-hydroxyvitamin D levels measured on the day of FET (time frame: Vitamin D level tested on the day of FET.). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07681115, which also lists 7 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Jul 2026.