Associations between reproductive factors and frailty in middle-aged and older women: evidence from the China health and retirement longitudinal study

BACKGROUND: Amid global aging, frailty significantly threatens the health of middle-aged and older women. This study is the first to explore the association between reproductive factors (age at first livebirth, number of biological children, reproductive period, age at menopause, age at menarche, and history of abortion) and frailty among middle-aged and elderly Chinese women. METHODS: Based on the 2014 life history survey and 2018 cross-sectional data from the China health and retirement longitudinal study (CHARLS), 2,948 female participants aged 45 years and above were included in the analysis. Frailty status was assessed using a Frailty Index (FI), constructed from 50 health deficit indicators. Data on reproductive factors, including age at first livebirth, number of biological children, reproductive period, age at menopause, age at menarche, and history of abortion were collected. Multivariable logistic regression models and restricted cubic spline analyses were used to examine the associations between frailty and reproductive factors. RESULTS: The study found that, compared with participants who had two children, those with three or more children had a 26.6% higher risk of frailty. Women with menarche at age 18 or older had a 30.1% higher frailty prevalence than those with menarche at 15 or younger. Similarly, those who reached menopause at age 55 or older had a 57.4% higher prevalence of frailty compared to those who experienced menopause between ages 45 and 55. In addition, a history of abortion was more strongly associated with an increased prevalence of frailty in women, whereas the reproductive period ≤ 33 years appeared to be a protective factor. No significant association was found between age at first livebirth and frailty. CONCLUSIONS: The findings suggest that the risk of developing frailty among middle-aged and older Chinese women is strongly associated with specific reproductive factors, including number of biological children, age at menarche, history of abortion, and age at menopause. These findings provide potential reproductive health indicators for the accurate clinical identification of frailty, offering a scientific foundation for developing targeted prevention and intervention strategies that can help alleviate the disease burden associated with frailty in an aging society.