To explore relationships among low back pain knowledge, fall fear, exercise self-efficacy and kinesiophobia in pregnant women with pregnancy-related low back pain (PLBP) through a chain mediating model. This study used a cross-sectional survey and utilized convenience sampling from August to December 2023 at a third-class hospital in Wuxi, China. A total of 325 PLBP pregnant women were chosen as the subjects of this study. Sociodemographics and information about low back pain knowledge, low back pain knowledge, fall fear, exercise self-efficacy, and kinesiophobia were collected. Path analysis was used to analyze the cross-sectional data. The results of this study found that low back pain knowledge can directly affect kinesiophobia (β = -0.489, p <
0.001). Fall fear and exercise self-efficacy play a significant mediating role between low back pain knowledge and kinesiophobia, with an overall mediating effect value of 0.202. After including fall fear and exercise self-efficacy, the direct effect value of low back pain knowledge on kinesiophobia was - 0.287. Low back pain knowledge in PLBP pregnant women can significantly and negatively predict their kinesiophobia. Between low back pain knowledge and kinesiophobia, there was not only an independent mediating effect of fall fear and exercise self-efficacy but also a chain mediating effect.