Recent years have seen an increase in the number of pregnant women whose weight gain during pregnancy exceeds the recommended range. This study was intended to determine the relationships among demographic attributes, key perceptual factors, and gestational weight gain (GWG).

This cross-sectional study was conducted between April and July 2022. First-time pregnant women beyond 36 weeks of gestation who were recruited via social media completed an online survey. Data were analyzed using one-way ANOVA, chi-square test, and logistic regression, all performed using SPSS software.

Of the 369 participants, 63 (17.1%) exceeded the recommended GWG guidelines, while 148 (40.1%) fell within the recommended range, and the remaining 158 (42.8%) had inadequate GWG. Being overweight or obese before pregnancy significantly increased the risk of excessive GWG (p < .001). This risk was also significantly greater for women with low internal weight locus of control (OR = 0.58, 95% CI 0.41~0.82), high external weight locus of control (OR = 1.75, 95% CI 1.31~2.34), and negative body image (OR = 0.62, 95% CI 0.51~0.75).

The growing trend of excessive GWG among pregnant women is influenced by a combination of prepregnancy body mass index (BMI) and perceptual factors, including weight locus of control and body image. These findings underscore the need to implement weight management intervention strategies before pregnancy, taking into consideration BMI, and to enhance positive body image and internal locus of control.