Introduction Most of conclusions on the relationship between age and reproductive health in aging men relied on cross-sectional data. Aim To better characterize the natural degradation trajectory of reproductive health of aging men based on longitudinal data. Methods A community cohort study was performed in randomly selected men 40 to 80 years old, initiated in 2012 and followed up in 2014 and 2016. Participants were investigated by face-to-face structured interview, including demographic information and International Index of Erectile Function (IIEF-5) and Aging Males’ Symptoms (AMS) scales. Main Outcome Measures The differences among the 3 assessments of IIEF-5 and AMS were analyzed, and progression trajectories were traced. Results The high degree of variability on AMS and IIEF-5 was evident across individual subjects, as was the variability within individuals. The average IIEF-5 score of 248 subjects decreased from 16.9 to 14.1 during the 4 years, and the total AMS score increased from 22.6–27.0 (P < .001). Longitudinal data, both of individuals and of groups, showed the more rapid increase or decrease on AMS or IIEF-5 scores over 4 years in the 61–70 age group than in other age groups. Clinical Implication The evidence of the greatest changes on AMS and IIEF-5 scores in the 61–70 age group prompts the importance of early intervention to postpone the degradation of reproductive health. Strength & Limitations Compared with cross-sectional data, longitudinal data can provide a more natural progression trajectory of reproductive health of aging male individuals. The low follow-up rate might affect the parameter estimation to some extent. Conclusion Cohort data over 4 years’ follow-up showed more abrupt changes on AMS and IIEF-5 scores in the 61–70 age group than in other age groups.

The objective of the current study was to explore the relationship between longitudinal change in body mass index (BMI) and reproductive hormones in middle-aged and elderly Chinese men. A cohort study was conducted in a rural area of China. Local male residents aged 40–80 years were recruited at baseline in 2012 and were followed up in 2016. Information about weight, height, waist circumference, sex hormones, smoking status, and medical history were obtained. The change in BMI reported no significant relationship with the change in total testosterone (TT), calculated free testosterone (cFT), and bioavailable testosterone (BioT) in Pearson correlation analyses. When the change in BMI was divided into three groups—“great loss,” “normal fluctuation,” and “great gain”—TT, cFT and BioT had the highest increase (or the lowest decrease) in men with “normal fluctuation” in BMI compared with the other two groups. The advantage of maintaining a stable BMI was more evident for those who were overweight, non-smoking, and disease-free. There was a tendency of a continuous increase in cFT and BioT with BMI increase in smoking and diseased populations. Maintaining a stable BMI is associated with maintaining normal levels of reproductive hormones, especially in overweight, non-smoking, and healthy men aged over 40 years.