Duration of the menopausal transition is longer in women with young age at onset: the multiethnic Study of Women's Health Across the Nation.
Level 3 - non-randomized controlled study
Prospective longitudinal multiethnic cohort study
PubMed 27676632 · doi:10.1097/GME.0000000000000736
What was done
Researchers analyzed data from 1,145 women across four sites of the Study of Women's Health Across the Nation (SWAN) menstrual calendar substudy (1996–2006). The cohort included African American, white, Chinese, and Japanese women with an identified start of the menopausal transition and complete covariate data. Participants completed daily menstrual calendars, monthly hormone therapy questionnaires, baseline assessments, and annual measures of height, weight, and smoking status. Cox proportional hazards models were used to analyze factors influencing the age at transition onset and its duration to the final menstrual period.
What was found
Adjusted median duration of the menopausal transition ranged from 8.57 years in the youngest age-at-onset quartile to 4.37 years in the oldest quartile (P < 0.001). Cigarette smoking was associated with earlier onset (P < 0.001) and shorter duration (P < 0.001). African American women had a longer transition duration than white women (P = 0.012). Body mass index was associated with later onset (P = 0.001) but had no significant association with duration.
Why it matters
Women entering perimenopause at younger ages spend nearly twice as long in transition as those who enter at older ages. This demonstrates that age at onset is a major determinant of transition length, informing clinical expectations and counseling.
Limits
The abstract provides median durations and p-values but lacks hazard ratios, confidence intervals, and the specific age bounds defining each quartile. The analysis is limited to participants with complete daily calendar tracking and four specific racial/ethnic groups from select US sites.
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