An observational study in Vitamin D Deficiency and Pregnancy, sponsored by University of Évora. Active, not recruiting at 3 sites in Portugal. Open to female participants aged 16 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-30.
Sponsored by University of Évora · Observational
The VitDTracking study focuses on the relevance of maternal vitamin D levels and their association with prematurity, aiming to improve maternal and child health outcomes, particularly by reducing avoidable preterm births. In Portugal, vitamin D levels during pregnancy have never been studied. Epidemiological data from other countries reveal a high prevalence of vitamin D deficiency/insufficiency, especially in pregnant women.
The hypovitaminoses prevalence remains high even with a supplementation dosage of 400 to 600 IU/day during pregnancy (dosage used in Portugal), which is considered as a suboptimal dose. This phenomenon is associated with adverse maternal and child outcomes, such as intrauterine growth restriction, preeclampsia, cholestasis, hypertension, and gestational diabetes as major causes of prematurity.
Additionally, the Portuguese population has a higher prevalence of genome alterations that confer a lower capacity to produce vitamin D from sunlight exposure. These genetic characteristics are present in about 19% of the population, representing a prevalence four times higher than the European average (19% versus 4.75%), leading to a higher predisposition to vitamin D deficiency.
This observational study involves the implementation of multicenter recruitment centers. Data collection will take place in healthcare organizations in the Alentejo region (Évora, Beja, Portalegre, and Elvas) with a minimum total sample of 1000 pregnant women, integrating both primary and specialized healthcare, with local healthcare professionals, doctors, and nurses as collaborators.
The study will measure vitamin D levels during pregnancy and their impact on outcome indicators related to prematurity. The aim is to assess the impact of the prevalence of vitamin D deficiency on prematurity outcomes. This involves monitoring vitamin D levels in prenatal and postnatal surveillance, adding this biomarker to routine blood collections. Biometric and biochemical data collection will occur at two distinct time points. The first collection will take place during the first prenatal surveillance appointment, preferably in the first trimester. The second collection will occur postpartum, during the hospitalization period.
The study will also assess maternal vitamin D deficiency and associated factors in the Alentejo region. It aims to identify the existence of genetic polymorphisms related to vitamin D and assess associations with adverse clinical outcomes related to prematurity. This involves requesting genetic analysis by the local medical collaborator and collecting saliva from the pregnant woman (non-invasive method) for the study of polymorphisms in seven genes, integrating the analysis of 18 genetic variants that play a role in the metabolism, transport, degradation and downstream pathways of vitamin D. Saliva samples from pregnant women will be collected during hospitalization before or after birth.
801 studies on the registry are indexed under Vitamin D Deficiency; 60 are open to participants now.
This study's enrollment of 2,000 is above the median of 138 across 185 observational studies indexed under Vitamin D Deficiency.
Browse Vitamin D Deficiency studies →University of Évora is the lead sponsor of 34 studies on the registry; 10 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Pregnant women's in the Alentejo region
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Other: Exposure
Other: Exposure
Other: Exposure
Maternal vitamin D levels during pregnancy (serum 25-hydroxyvitamin D levels)
Differences in the rate of Prematurity with different maternal Vitamin D levels
Prematurity Rate in percentage
Time frame: Blood samples will be taken from pregnant women up to the 13th week of pregnancy and then at the second collection point up to 48 hours after the birth (after participant enrollment; two collection points)
Differences in Birth Weight with different maternal Vitamin D levels
Birth Weight in grams
Time frame: Blood samples will be taken from pregnant women up to the 13th week of pregnancy and then at the second collection point up to 48 hours after the birth (after participant enrollment; two collection points)
Differences in Apgar Scores with different maternal Vitamin D levels
Apgar Scores in Scale (\<7 or ≥7)
Time frame: Blood samples will be taken from pregnant women up to the 13th week of pregnancy and then at the second collection point up to 48 hours after the birth (after participant enrollment; two collection points)
Differences in the number of admissions to the Neonatal Intensive Care Unit with different maternal Vitamin D levels
Number of admissions to the Neonatal Intensive Care Unit in percentage
Time frame: Blood samples will be taken from pregnant women up to the 13th week of pregnancy and then at the second collection point up to 48 hours after the birth (after participant enrollment; two collection points)
Differences in the Neonatal Morbidity rate with different maternal Vitamin D levels
Neonatal Morbidity rate in percentage
Time frame: Blood samples will be taken from pregnant women up to the 13th week of pregnancy and then at the second collection point up to 48 hours after the birth (after participant enrollment; two collection points)
Differences in the Neonatal Mortality rate with different maternal Vitamin D levels
Neonatal Mortality rate in percentage
Time frame: Blood samples will be taken from pregnant women up to the 13th week of pregnancy and then at the second collection point up to 48 hours after the birth (after participant enrollment; two collection points)
Differences in the number of Neonatal Infections with different maternal Vitamin D levels
Number of Neonatal Infections in percentage
Time frame: Blood samples will be taken from pregnant women up to the 13th week of pregnancy and then at the second collection point up to 48 hours after the birth (after participant enrollment; two collection points)
Differences in the Number of Congenital Malformation diagnoses with different maternal vitamin D levels
Number of Congenital Malformation diagnoses in percentage
Time frame: Blood samples will be taken from pregnant women up to the 13th week of pregnancy and then at the second collection point up to 48 hours after the birth (after participant enrollment; two collection points)
Differences in the presence of vitamin D-related polymorphisms with different maternal levels of vitamin D
Differences will be assessed following the defined outcome indicators related to prematurity
Time frame: Saliva samples from pregnant women will be collected during admission to the hospital or up to 48 hours after delivery (after participant enrollment; single collection point)
Differences in maternal vitamin D levels between the three groups/cohorts related to prematurity
Time frame: Through study completion, an average of 3 months
Differences in maternal vitamin D levels between the three groups/cohorts related to birth weight
Time frame: Through study completion, an average of 3 months
Differences in maternal vitamin D levels between the three groups/cohorts related to Apgar scores
Time frame: Through study completion, an average of 3 months
Differences in maternal vitamin D levels between the three groups/cohorts related to admission to the Neonatal Intensive Care Unit
Time frame: Through study completion, an average of 3 months
Differences in maternal vitamin D levels between the three groups/cohorts related to neonatal morbidity
Time frame: Through study completion, an average of 3 months
Differences in maternal vitamin D levels between the three groups/cohorts related to neonatal mortality
Time frame: Through study completion, an average of 3 months
Differences in maternal vitamin D levels between the three groups/cohorts related to neonatal infections.
Time frame: Through study completion, an average of 3 months
Differences in maternal vitamin D levels between the three groups/cohorts related to the diagnosis of congenital malformations
Time frame: Through study completion, an average of 3 months
Differences in the presence of vitamin D-related polymorphisms between the three groups/cohorts associated with prematurity
Time frame: Through study completion, an average of 3 months
Differences in the presence of vitamin D-related polymorphisms between the three groups/cohorts associated with birth weight
Time frame: Through study completion, an average of 3 months
Differences in the presence of vitamin D-related polymorphisms between the three groups/cohorts associated with Apgar scores
Time frame: Through study completion, an average of 3 months
Differences in the presence of vitamin D-related polymorphisms between the three groups/cohorts associated with admission to the Neonatal Intensive Care Unit.
Time frame: Through study completion, an average of 3 months
Differences in the presence of vitamin D-related polymorphisms between the three groups/cohorts associated with neonatal morbidity
Time frame: Through study completion, an average of 3 months
Differences in the presence of vitamin D-related polymorphisms between the three groups/cohorts associated with neonatal mortality
Time frame: Through study completion, an average of 3 months
Differences in the presence of vitamin D-related polymorphisms between the three groups/cohorts associated with neonatal infections
Time frame: Through study completion, an average of 3 months
Differences in the presence of vitamin D-related polymorphisms between the three groups/cohorts associated with the diagnosis of congenital malformations
Time frame: Through study completion, an average of 3 months
Plan to share: No
Started Nov 2023 (actual). Primary completion is estimated for Dec 2026, 37 months after the start.
Of 61 non-industry observational studies under Vitamin D Deficiency, half reached primary completion within 19 months of starting (the median), counting those still running; a quarter within 9 and three quarters within 40. This study's planned 37 months is above that.
Counting every sponsor, half of 62 studies reached it within 19 months; a quarter within 9 and three quarters within 40.
Since we started tracking on Sep 25, 2026, the dates moved once, on Sep 30, 2026: primary completion Dec 2024 → Dec 2026 and completion Dec 2025 → Jun 2027.
Earlier changes are on the record history on ClinicalTrials.gov ↗
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is active, not recruiting, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
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University of Évora