Is there a threshold at which vitamin D status during pregnancy optimizes maternal and neonatal health outcomes? A focus on bone and gestational diabetes
Bibliographic record
Abstract
Low vitamin D status, defined by circulating 25-hydroxy vitamin D (25(OH)D) <50 or <75 nmol/L is prevalent among pregnant women and has been associated with neonatal rickets and gestational diabetes mellitus (GDM). Osteocalcin (OC), a bone formation biomarker, linking the bone to glucose metabolism is stimulated by 1,25-dihydroxyvitamin D (1,25(OH)2D), the active form of vitamin D. In the first study, maternal serum 25(OH)D and OC were explored at early and mid-gestation in GDM (case, n=48) vs healthy (control, n=48) Caucasian pregnant women. Maternal serum 25(OH)D was not different (p=0.80) while OC was higher (p=0.006) in those with GDM vs controls across all trimesters. There are no vitamin D dose-response studies on glucose tolerance and bone outcomes in human and animals. Animal studies commonly use isoflurane, an anaesthetic, which may affect OC and glucose concentrations. Therefore, in the second study, the effect of isoflurane exposure was studied on bone biomarkers in guinea pigs (n=10) at 5, 9 wk of age and glucose at postpartum (26 wk). Isoflurane increased OC during rapid growth (p<0.001) and increased glucose at postpartum (p<0.0001). In the third study, the dose-response effect of maternal dietary vitamin D was investigated on maternal glucose tolerance. Female 4 mo old guinea pigs (n=45) were randomized to isocaloric diets containing different dosages of vitamin D3 (0, 0.25, 0.5, 1 and 2 IU/g diet) from mating to delivery. The results revealed no differences in AUC (area under the curve) for maternal glucose from the OGTT (oral glucose tolerance test) across groups during pregnancy. However, an inverse association was observed between pre-mating 25(OH)D and AUC for glucose. In the fourth study, the dose-response effect of dietary vitamin D was studied on maternal and neonatal bone outcomes. In the sows, a positive dose-response (p<0.0001) was observed in plasma 25(OH)D but 1,25(OH)2D reached a plateau once dietary vitamin D was >0.5 IU/g diet. No differences in areal (aBMD) or volumetric bone mineral density (vBMD) or biomarkers were observed among maternal groups. In the 2 d guinea pig neonate: both 25(OH)D and 1,25(OH)2D followed a dose-response (p<0.0001) to maternal diet, femoral aBMD was 10 % higher in the 2 IU vs all groups except the 0 IU (p=0.04). At the neonatal distal femur and proximal tibia, response to maternal diet was U-shaped for trabeculae (Tb.) vBMD. Expansion of the femur growth plate was observed in the 0 IU vs all other groups. In conclusion, vitamin D status may be more important at pre-mating than mid-gestation in protecting against pregnancy induced glucose intolerance. To reflect normal metabolism, measurements of OC and glucose prior to isoflurane anaesthesia are recommended. Maternal vitamin D status below recommendations may result in features similar to rickets in the offspring but status above recommendations may not be advantageous to the bone in the guinea pig.
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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 | 0.003 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".