Association of lifetime lactation and characteristics of menopause: a longitudinal cohort study
Bibliographic record
Abstract
Abstract Background Lactation has many established benefits for women’s long-term health; however, its influence on menopause is less clear. This study investigated the association between lifetime duration of lactation and the timing and type of menopause in midlife women. Methods We analyzed survey data on 19,783 parous women aged 40 to 65 years at enrollment in the Alberta’s Tomorrow Project (2000–2022), a prospective community-based cohort study in Alberta, Canada. Duration of lifetime lactation across all births was categorized as: <1 month (reference group; 19.8% of women), 1–3 months (12.1%), 4–6 months (11.7%), 7–12 months (18.8%), and ≥ 13 months (37.7%). Women were classified as premenopause, natural menopause (age at 1 year after the final menstrual period), surgical menopause (age at bilateral oophorectomy), or indeterminate menopause (age at premenopausal hysterectomy with ovarian preservation). Flexible parametric survival analysis and multinomial logistic regression were used to analyze menopause timing and type, respectively, according to lactation status and controlling for birth year, education, parity, hormonal contraceptive use, and smoking. Results In a dose-response manner, longer lactation was associated with reduced risk of natural menopause before age 50 (for ≥ 13 months of lactation, adjusted hazard ratio at age 45: 0.68, 95% CI 0.59–0.78), surgical menopause before age 55 (age 45: 0.56, 0.50–0.63), and indeterminate menopause before age 50 (age 45: 0.75, 0.69–0.82). Longer lactation was associated with lower odds of surgical (adjusted odds ratio 0.54, 95% CI 0.45–0.66) and indeterminate menopause (0.63, 0.55–0.73), compared to natural menopause. Conclusions Optimizing the timing of natural menopause and reducing risks of early surgical and indeterminate menopause may be novel maternal benefits of breastfeeding.
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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 | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.104 | 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".