Ito A, Hayashi K, Suzuk S, et al. - The present study was conducted to examine whether BMI trajectory, lifestyle and reproductive factors are correlated with knee pain risk among middle-aged women. This study included a total of 7,434 women aged over 40 years who responded to the 10-year self-administered follow-up questionnaire. The primary endpoint was self-reported knee pain at the 10-year follow-up. Researchers examined BMI (normal or overweight) trajectory data from a baseline survey to the 10-year follow-up survey utilising group-based trajectory modelling. It was demonstrated that the lost weight group had a lower risk than the remained overweight group and the gained weight group and did not provide statistically significant risks for knee pain. In women, weight reduction and maintaining a normal BMI in middle age was important for the prevention of knee pain.