No Sex Differences in Bone Mineral Accretion From 1 to 12 Months of Age Among a Sample of Healthy Term Breastfed Infants From Montreal, Canada
Bibliographic record
Abstract
To investigate sex differences in bone mass including whole body (WB) bone mineral content (BMC), lumbar spine (LS) BMC and LS bone mineral density (BMD) during infancy. This is a secondary analysis of data from a double-blinded randomized clinical trial (NCT00381914), in which healthy term breastfed infants were randomized to 1 of 4 doses of oral vitamin D supplementation (400−1600 IU/d) at 1 mo of age (+/− 2 wk). Serum 25-hydroxyvitamin D (25(OH)D) using liquid chromatography-tandem mass spectrometry, and BMC and BMD using dual-energy x-ray absorptiometry (Hologic) were measured at 1, 3, 6, 9, and 12 mo of age (+/- 2 wk). No effect of supplementation on BMC (WB and LS) and BMD (LS) was reported in the primary study. Infants (32 males (M), 31 females (F)) with baseline serum 25(OH)D ≥ 50 nmol/L, based on the Institute of Medicine's cutoff in support of bone health, were included in this secondary analysis. Differences between sexes over time in BMC and BMD were tested using mixed model repeated measures ANOVA accounting for the fixed effects of sex, time, and sex*time and the random effect of infant ID, with Tukey multiple comparison test. Infants were on average 39.5 ± 1.1 wk gestational age, with weight for age z-score of 0.40 ± 0.97 at birth. There were no differences between sexes in mineral accretion rates of the WB (M: 12.94 ± 8.83, F: 12.20 ± 7.71 g/mo; p = 0.36) and at the LS (M: 0.26 ± 0.28, F: 0.22 ± 0.31 g/mo; p = 0.33) between 1 to 12 mo of age, but M had higher overall WB BMC than F (166.16 ± 57.30 vs. 153.34 ± 50.06 g, p = 0.03). When adjusted for weight or length, no sex differences were observed over time in WB BMC per weight (M: 22.02 ± 2.29, F: 22.20 ± 2.27 g/kg; p = 0.58) and WB BMC per length (M: 2.47 ± 0.60, F: 2.34 ± 0.53 g/cm, p = 0.06). Similarly, when using the WB less head BMC measurement, no sex differences were observed (M: 84.80 ± 30.24, F: 78.41 ± 7.57 g; p = 0.07). In addition, LS BMC (M: 3.77 ± 1.34, F: 3.75 ± 0.22 g; p = 0.93) and LS BMD (M: 0.273 ± 0.051, F: 0.284 ± 0.054 g/m2; p = 0.10) did not vary by sex. Sex differences in BMC in infancy, if any, are mostly driven by infant size. Based on BMC and accretion rates, sex-specific normative data do not appear required during infancy. Canadian Institutes of Health Research, Nutricia Research Foundation, and the Canadian Foundation for Innovation.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".