Effects of Vitamin D on Health Promotion During Pregnancy and Its Impact on Prematurity-Related Outcome

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.

Eligibility Criteria:
Inclusion Criteria:

* Pregnant women's living in the Alentejo region aged 16 years or older, who after disclosure and clarification of doubts, agree to participate in the study with signed informed consent.

Exclusion Criteria:

* Language barrier (lack of basic understanding of Portuguese).