(1) Background: China has the highest number of rural-to-urban floating women in the world, and the majority of them are of childbearing age. However, few studies have focused on maternal self-efficacy (MSE) for these women. This research aims to explore MSE and its influencing factors for primiparous women among the rural-to-urban floating population in China. (2) Methods: A quantitative longitudinal study was conducted, and primiparous women from the floating population were recruited in China. Face-to-face demographic questionnaires were collected from obstetric wards by the researchers, three days postpartum. The 6-week and 12-week questionnaires, including the Self-efficacy in Infant Care Scale (SICS), the Edinburgh Postnatal Depression Scale (EPDS), and the Postpartum Social Support Scale (PSSS), were sent to participants by wechat or email to measure MSE, postnatal depression, and social support, respectively. The completed 6-week and completed 12-week questionnaires were returned to the researchers. (3) Results: The mean MSE scores at 6 and 12 weeks postpartum were 67.16 (SD = 14.35) and 68.71 (SD = 15.00). The variables of social support, postnatal depression, whether women attended parenting training, baby fussiness, baby health, maternal educational level, occupation, and family income affected MSE at the two time points. (4) Conclusions: Primiparous women among the rural-to-urban floating population had a low MSE level. As a vulnerable and special group, more attention should be paid to the negative parenting status of floating women by health workers and family members. Effective measures must be taken to improve the floating women's accessibility to parenting training from health services to strengthen their social support and alleviate postpartum depression. Health professionals should be more concerned with floating women with relatively low MSE levels, such as new mothers with lower education, poor working and living conditions, unhealthy babies, and babies with fussy temperaments.
Keywords: Mainland China; floating women; postnatal depression; postpartum women; self-efficacy.