Menarche, menopause and reproductive span in relation to frailty trajectories in Chinese women

Frailty is a dynamic condition, but the influence of female reproductive factors on its long-term trajectories remains unclear. This study aimed to examine whether age at menarche (AAM), age at menopause (AMP) and reproductive span (RS) predict long-term frailty trajectories in middle-aged and older women. Data were analyzed from four waves (2011–2018) of the China Health and Retirement Longitudinal Study (CHARLS). Frailty was measured using the frailty index (FI), and trajectories were identified via latent category growth modeling (LCGM). Logistic regression and restricted cubic spline analyses assessed the associations of reproductive factors with FI trajectories. Among 2775 women, FI trajectories were classified into two groups: ‘low-stable’ (N = 1961) and ‘high-rising’ (N = 814). Compared with women who had menopause at ages 46–54 years, those with AMP ≤45 years (odds ratio [OR] = 1.377, 95% confidence interval [CI]: 1.073–1.766) or AMP ≥55 years (OR = 1.558, 95% CI: 1.113–2.181) had higher odds of following the ‘high-rising’ frailty trajectory. Similarly, RS < 26 years (OR = 1.810, 95% CI: 1.277–2.566) or RS ≥40 years (OR = 1.734, 95% CI: 1.123–2.678) were associated with increased odds of the ‘high-rising’ trajectory. AAM was not significantly associated with frailty trajectories. Early or late menopause and extreme RS are associated with worsening frailty trajectories. Frailty (a state of increased vulnerability to health problems) often changes over time, but little is known about how women’s reproductive experiences, such as age at first menstruation (menarche), age at menopause and reproductive span, might affect this decline. We studied 2775 middle-aged and older Chinese women from 2011 to 2018, tracking their frailty levels using a standard measure. We grouped women into two frailty patterns: those who stayed relatively healthy (‘low-stable’) and those whose frailty worsened over time (‘high-rising’). We then tested whether reproductive factors predicted these patterns. Women who entered menopause very early (age ≤45 years) or very late (age ≥55 years) had about 40–50% higher odds of worsening frailty. Similarly, those with very short (