Calcium Supplementation in Pregnancy: A Systematic Review of Clinical Studies
Bibliographic record
Abstract
Background and Objectives: Calcium is an essential mineral that plays a vital role in fetal development and maternal health during pregnancy. The World Health Organization recommends a daily calcium intake of 1.5–2 g for pregnant adult women. Calcium deficiency during gestation may lead to complications, such as gestational hypertension, preeclampsia, loss of bone mineral density, impaired fetal development, and other adverse pregnancy outcomes. The aim of the present review is to evaluate the current clinical evidence on calcium intake during pregnancy. Methods: The present systematic review was conducted according to the PRISMA 2020 statement by searching two major databases, PubMed and Mendeley. The study protocol was registered in the Open Science Framework (DOI: osf.io/rvj7z). Inclusion criteria were clinical trials on calcium supplementation during pregnancy. Exclusion criteria were clinical guidelines, reviews, case reports, case series, letters, and commentaries. The Newcastle–Ottawa Scale was used to assess the risk of bias in the included studies. Results: Initially, 451 publications were identified, and after removal of duplicates and screening of titles and/or abstracts and/or full texts, 34 studies were included. The number of participants ranged between 30 and 22,000 women. Calcium supplementation was associated with lower incidence of and less severe gestational hypertension and preeclampsia, lower risk of preterm birth, longer pregnancy duration and higher neonatal birth weight, and improved maternal bone mineral density postpartum. When the doses were split up into smaller doses, the benefits were strongest with high-dose regimens (1.5–2 g/day). Conclusions: Calcium supplementation during pregnancy has beneficial effects on maternal and neonatal health, especially in populations with insufficient dietary daily calcium intake and women at high risk of hypertensive disorders. Daily dose may vary according to individual needs, daily dietary calcium intake, and general health status. Further large-scale randomized controlled trials (RCTs) are necessary to confirm these findings.
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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 | 0.011 | 0.048 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.012 | 0.009 |
| Bibliometrics | 0.014 | 0.016 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.003 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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 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".