Several theoretical models highlight the importance of appearance-based pressures to conform to sociocultural body ideals in the development and maintenance of body dissatisfaction and disordered eating. Qualitative data suggest that perinatal women experience significant pressure to lose pregnancy-related weight, yet there is no validated quantitative measure of appearance-based sociocultural pressures during pregnancy. This pressure may be especially pronounced in female Service members due to the fitness requirements of serving in the U.S. military. This study sought to develop and provide preliminary validation for the Pressure to Lose Pregnancy-Related Weight (PLPW) scale. Participants ( N = 192) were pregnant U.S. military active-duty Service women who completed an online survey at two timepoints (during their second and third trimesters, about 12 weeks apart). An exploratory factor analysis revealed all four items of the PLPW loaded onto a single factor (eigenvalue = 3.13). The internal consistency (Ω=.94) and test-retest reliability (ICC=.78, r = .78, p < .001) of the unidimensional scale were supported, as was predictive validity from the second to third trimesters in relation to a measure of body dissatisfaction (β=.11, F (2, 176)= 318.4, p < .001). Findings provide preliminary support for the basic psychometric properties of the 4-item unidimensional PLPW. Future research is recommended to characterize the potentially unique influences of different sources of pressure to lose pregnancy-related weight, and further psychometric evaluations of the PLPW in other perinatal samples is needed. • Perinatal women report significant appearance-based pressures despite no validated measures. • Exploratory factor analysis indicated four items loaded onto a single factor. • The scale demonstrated excellent internal consistency and good test-retest reliability. • Pressure to lose pregnancy-related weight predicted later body dissatisfaction.