Advantaged socioeconomic position (SEP) is associated with lower body image satisfaction (BIS) among women. However, motherhood and social trajectory (an individual's path from childhood SEP to adulthood SEP) could change this relationship. We aimed to assess the association between social trajectory and BIS immediately before getting pregnant in primiparous and multiparous mothers of a birth cohort. The birth cohort Generation XXI was assembled after delivery, in Porto, in 2005-2006. This analysis includes 5,470 women. Women's and their parents' education were used as indicators of adulthood and childhood SEP, respectively. Social trajectory was classified as stable-high, upward, stable-low, downward, according to both education variables. BIS was assessed with Stunkard silhouettes immediately after birth as the difference between perceived body size before the index pregnancy and ideal body size. Odds ratios (OR) between social trajectory and BIS were computed using multinomial logistic regression (women satisfied with body image were the outcome reference category), adjusting for age and prepregnancy body mass index. In primiparous women, no association was found between childhood SEP, adulthood SEP or social trajectory and feeling too small or too large regarding their ideal figure. Multiparous women with a downward social trajectory presented a higher likelihood of dissatisfaction [too small: adjusted OR 2.21, 95 % confidence interval (95 % CI) 1.10-4.46; too large: adjusted OR 1.64, 95 % CI 1.07-2.51]. Downward social trajectory was associated with a higher likelihood of dissatisfaction with body image in multiparae, while there was no effect among primiparae.