Background: More than half of the pregnant women are affected by lumbopelvic pain (LPP) in their daily lives. Physical activity (PA) contributes to LPP relief. There are several reports on exercise habits, including the recommended activity intensity (moderate) and time spent (at least three times a week); however, only a few detailed reports on household/child-rearing and occupational activity are available. Therefore, this study explored the relationships between housework/child-rearing, occupational hours, and LPP. Methods: This study included 95 pregnant females who attended an obstetrics and gynecology hospital. The participants were divided into two groups based on the results of an interview on the presence of LPP and classified by intensity or category using the Pregnancy Physical Activity Questionnaire (PPAQ-J). The Wilcoxon signed-rank test was used to compare PA between the two groups. When a significant difference was observed, we performed logistic regression analysis using body mass index (BMI) as an adjustment variable. Results: There were 16 females with LPP and 17 women without LPP in the third trimester. There were significant associations between the PPAQ scores of housework/child-rearing activities and LPP in the third trimester. No significant differences in any category of PPAQ scores were observed between the groups with and without LPP in the first and second trimester of pregnancy. Conclusions: Our study showed the association between PA and LPP in the third pregnancy. Pregnant females with LPP tended to spend more time on housework and child-rearing necessary for their lives. The duration of housework and child rearing should be reduced because of prolonged standing and the burden on the lumbar area.