Prevalence of Vitamin D Deficiency in Pregnant Women: Systematic Review and Meta-analysis
Bibliographic record
Abstract
CONTEXT: Vitamin D is an essential steroid prehormone whose effects have garnered significant interest during pregnancy and lactation. Adequate vitamin D levels are crucial for embryonic implantation, immune modulation, and preventing adverse maternal outcomes such as preeclampsia, gestational diabetes, and preterm birth. OBJECTIVES: To estimate the prevalence of vitamin D deficiency in each trimester of pregnancy. DATA SOURCES: This is a systematic review and meta-analysis, conducted according to the PRISMA guidelines. Online databases were searched from inception to July 2023, including Medline/PubMed, Embase, and LILACS. DATA EXTRACTION: All English, Spanish, and Portuguese articles that specified the prevalence of vitamin D deficiency in each of the 3 trimesters of pregnancy were included. All screening and data extraction were performed independently by 2 authors. Risk-of-bias assessment was performed using the Newcastle-Ottawa Scale. DATA ANALYSIS: A total of 2627 articles were retrieved, and after evaluating eligibility criteria, 116 full-text articles were included. These comprised observational studies, totaling 127 290 pregnant women who underwent serum 25(OH)D evaluation. Vitamin D deficiency is a common condition among pregnant women. The meta-analysis revealed that 68% (95% CI, 60%-76%) of pregnant women had 25(OH)D <30 ng/mL in the first trimester, 81% (95% CI, 74%-87%) in the second trimester, and 70% (95% CI, 64%-75%) in the third trimester, indicating a widespread deficiency of this vitamin. CONCLUSION: A thorough analysis of the studies included in this review shows that hypovitaminosis D during pregnancy is a highly prevalent condition that occurs in all 3 trimesters. Given this high prevalence, these findings may be valuable for planning public health policies aimed at pregnant women. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42022343256.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.003 | 0.001 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".