Excessive weight gain, obesity, or insufficient weight gain during pregnancy can adversely affect both the mother and her offspring. This study aims to investigate the relationship between pregnant women's self-perception and beliefs and their body weight management during pregnancy. A cross-sectional survey involving 350 pregnant women in Changsha City was conducted from July to September 2023. Instruments included a sociodemographic data sheet, protective motivation questionnaire for pregnancy body quality management, and scales measuring body image, anxiety, self-efficacy, and social support. Univariate analysis and multiple linear regression were employed to identify factors influencing protective motivation for body quality management during pregnancy. The average score of the protective motivation questionnaire was 124 (SD = 13.07), suggesting a need for enhanced weight management. Key factors influencing protective motivation included household income, cooperation with healthcare workers, sources of pregnancy information, midnight snacking habits, prepregnancy exercise, body image, and self-efficacy (P < 0.05). The study highlights significant factors influencing pregnant women's motivation for body quality management. These include economic status, healthcare collaboration, information accessibility, lifestyle habits, and psychological factors. The findings underscore the need for healthcare professionals to integrate these factors into pregnancy care programs to improve body quality management.