An Investigation of the Effect of Vitamin D Level During Frozen Embryo Transfer (FET) in IVF and Pregnancy Outcomes
Vitamin D Insufficiency · In Vitro Fertilization and Embryo Transfer
What this study involves
The registry says this study is recruiting. Individual locations may have different availability.
- Study type
- Observational
- Phase
- Not applicable / not listed
- Age range
- 18 years - 40 years
- Sex eligible
- Female
- Healthy volunteers
- Not accepted
- Participants
- 126 Estimated
These are starting points, not an eligibility decision. The research team must review the full requirements.
About the research
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 full 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.
Who may be able to participate?
The list below is the sponsor’s full registry wording. It can include conditions, prior treatment, test results and other requirements. A match in search does not mean you qualify.
Inclusion:
- 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).
Exclusion:
- 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.
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.
Understand screeningTreatment, groups and participation
The registry may describe treatments and study duration without a complete visit calendar. Ask the study team for the exact schedule, procedures, risks, costs and alternatives. Keep your usual care plan unless your treating clinician tells you otherwise.
- Assignment
- Not reported
- Masking
- Not reported
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.
Other: No Intervention: Observational Cohort
No Intervention: Observational Cohort OTHER
There are no interventions in this study. This is an observational cohort study.
What researchers are measuring
Outcome measures describe what is being studied. They are not proof that a treatment works.
Primary measures
Concentration of serum 25-hydroxyvitamin D levels measured on the day of FET
Time frame: Vitamin D level tested on the day of FET.
Not reported in this registry record.
Clinical pregnancy test
Time frame: From enrollment on day of FET to 1 month post FET
Not reported in this registry record.
Secondary measures
Live birth rate, miscarriage rate, and preterm birth rate.
Time frame: From enrollment to six weeks post partum
Not reported in this registry record.
Review the complete result tables and limitations in the official record.
Open official results ↗Research locations (2)
The overall study status and a local site’s status can differ. Confirm that location’s availability before traveling.
2 locations
Fakih IVF Fertility Centre LLCAbu Dhabi, United Arab EmiratesRecruiting
First IVF Fertility CentreAbu Dhabi, United Arab EmiratesRecruiting
Study team and timeline
- Lead sponsor
- Fakih IVF Fertility Center
- Study start
- Jun 1, 2026 Actual
- Primary completion
- 2027-06 Estimated
- Study completion
- 2027-08 Estimated
- First posted
- Jul 2, 2026 Actual
- Last updated
- Nov 10, 2026 Actual
Official study contacts
Official study title
Vitamin D Levels and Pregnancy Outcomes Following Frozen Embryo Transfer (FET) in the UAE
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Source: ClinicalTrials.gov API v2. Information is submitted by sponsors and investigators. NLM does not approve the safety or science of all listed studies. Registry disclaimer.
Retrieved: Nov 12, 2026 · Last registry update: Nov 10, 2026