Effects of vitamin D levels during pregnancy on prematurity: a systematic review protocol
Bibliographic record
Abstract
INTRODUCTION: Prematurity is an urgent public health problem worldwide. Recent studies associate maternal hypovitaminosis D during pregnancy with an increased risk of prematurity. However, the evidence on this association remains inconclusive, and there is lack of consensus in the literature. The exact mechanism by which low vitamin D levels may increase the risk of preterm birth is not yet fully understood. Nevertheless, it is known that vitamin D may play a role in maintaining a healthy pregnancy by regulating inflammation and immunomodulation by acting on the maternal and fetal immune systems. Inflammation and immune dysregulation are both associated with preterm birth, and low vitamin D levels may exacerbate these processes. The results of this review may have important implications for clinical practice and public health policy, particularly regarding vitamin D supplementation during pregnancy. METHODS AND ANALYSIS: A systematic review of the literature will be conducted. The search will be performed in electronic databases: CINAHL; MEDLINE; Cochrane Central Register of Controlled Trials; Cochrane Library; Academic Search Complete; Information Science and Technology Abstracts; MedicLatina; SCOPUS; PubMed; and Google Scholar, with the chronological range of January 2018 to November 2022. The search strategy will include the following Medical Subject Headings or similar terms: 'Vitamin D'; '25-hydroxyvitamin D'; 'Hypovitaminosis D'; 'Pregnancy'; 'Pregnant women'; 'Expectant mother'; 'Prematurity'; 'Premature birth'; 'Premature delivery'; 'Preterm birth'; and 'Preterm labour'. This review will include quantitative primary studies, both experimental (clinical trials) and observational (cohort, cross-sectional, and case-control). The quality of each selected study and the results obtained will be assessed by two reviewers separately, using the Cochrane risk of bias tool for evaluating randomised clinical trials or the Newcastle Ottawa Scale for non-randomised studies, following the respective checklist. In case of disagreement, a third reviewer will be consulted. ETHICS AND DISSEMINATION: This study does not involve human subjects and therefore does not require ethics approval. The results will be disseminated through publication in a peer-reviewed scientific journal and through conference presentations. All changes made to the protocol will be registered in PROSPERO, with information on the nature and justification for the changes made. PROSPERO REGISTRATION NUMBER: CRD42022303901.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.039 | 0.041 |
| Meta-epidemiology (narrow) | 0.005 | 0.005 |
| Meta-epidemiology (broad) | 0.022 | 0.013 |
| Bibliometrics | 0.016 | 0.014 |
| Science and technology studies | 0.003 | 0.004 |
| Scholarly communication | 0.007 | 0.009 |
| Open science | 0.005 | 0.005 |
| Research integrity | 0.006 | 0.004 |
| Insufficient payload (model declined to judge) | 0.061 | 0.005 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".