Meta-analysis suggests that smoking is associated with an increased risk of early natural menopause.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational studies.
PubMed 21946090 · doi:10.1097/gme.0b013e318224f9ac
What was done
A meta-analysis of 11 studies retrieved from public literature databases was conducted to quantify the association between smoking and age at natural menopause (ANM). Studies were categorized into five dichotomous studies (evaluating early vs. late ANM using odds ratios) and six continuous studies (evaluating mean and standard deviation of ANM in smokers vs. non-smokers using weighted mean difference).
What was found
Smoking was significantly associated with early ANM across both formats: - Dichotomous studies: Pooled OR = 0.74 (95% CI, 0.60–0.91, P < 0.01); adjusted for heterogeneity, OR = 0.67 (95% CI, 0.61–0.73, P < 0.01). - Continuous studies: Pooled WMD = -1.12 (95% CI, -1.80 to -0.44, P = 0.04); adjusted for heterogeneity, WMD = -0.90 (95% CI, -1.58 to -0.21, P = 0.01).
Why it matters
This meta-analysis clarifies conflicting earlier reports by demonstrating that smoking is an independent risk factor for earlier natural menopause, bringing forward menopause by roughly one year.
Limits
The total number of human participants across the 11 included studies is not reported in the abstract. As an analysis of observational data, residual confounding cannot be ruled out, and the abstract provides no information on dose-response relationships (such as pack-years) or former smoking status.
Cited by
- supports Menopause is clinically defined as 12 consecutive months without a menstrual period.