Background: The aim of this study was to determine the impact of the COVID-19 pandemic on the levels of physical activity during the third trimester of pregnancy, life satisfaction and stress in women in late pregnancy and early postpartum. Methods: The study was conducted among 740 patients of maternity wards in Cracow hospitals on days 1–8 postpartum. Patients who were surveyed before the pandemic (December 2019–March 2020) were included in the prepandemic group (PPan: n = 252). The second group of women (COVID 1 group, Cov1: n = 262) was examined in the early stages of the pandemic (May–September 2020). In turn, participants who were surveyed during the population vaccination campaign (June–September 2021) were qualified to the COVID 2 group (Cov2: n = 226). The research tools used were the original questionnaire in addition to standardized questionnaires assessing physical activity in the last trimester of pregnancy (the Pregnancy Physical Activity Questionnaire); previous life satisfaction (the Satisfaction with Life Scale); and stress levels during the last month (the Perceived Stress Scale). Results: During the pandemic, women reduced the level of energy spent on total physical activity; nevertheless, statistically significant differences were found only between the PPan and Cov2 groups (p = 0.001). At the early stages of the pandemic, patients significantly reduced mobility activities (Cov1 vs. PPan: p < 0.001; Cov1 vs. Cov2: p = 0.007), while late in the pandemic they spent less energy on household activities (Cov2 vs. PPan: p = 0.002, Cov2 vs. Cov1: p = 0.002). There were no differences in the levels of stress and life satisfaction. Conclusions: The COVID-19 pandemic impacted the level of physical activity; however, it did not change levels of perceived stress and life satisfaction in women in late-stage pregnancy and in the early puerperium.