Background: Physical activity (PA) plays an important role in optimizing health outcomes throughout pregnancy. In many low-income countries, including Nepal, data on the associations between PA and pregnancy outcomes are scarce, likely due to the lack of validated questionnaires for assessing PA in this population. Here we aimed to evaluate the reliability and validity of an adapted version of Global Physical Activity Questionnaire (GPAQ) among a sample of pregnant women in Nepal. Methods: A pilot cohort of pregnant women (N=101; age 25.9±4.1 years) was recruited from a tertiary, peri-urban hospital in Nepal. An adapted Nepali version of GPAQ was administered to gather information about sedentary behavior (SB) as well as moderate and vigorous PA across work/domestic tasks, travel (walking/bicycling), and recreational activities, and was administered twice and a month apart in both the 2nd and 3rd trimesters. Responses on GPAQ were used to determine SB (min/day) and total moderate to vigorous PA (MVPA; min/week) across all domains. GPAQ was validated against PA data collected by a triaxial accelerometer (Axivity AX3; UK) worn by a subset of the subjects (n=21) for seven consecutive days in the 2nd trimester. Intra-class correlation coefficients (ICC) and Spearman’s rho were used to assess the reliability and validity of GPAQ.Results: Almost all of the PA in the sample was attributed to moderate activity during work/domestic tasks or travel. On average, total MVPA was higher by 50 minutes/week in the 2nd trimester as compared to the 3rd trimester. Based on the World Health Organization (WHO) guidelines, almost all of the participants were classified as having a low or moderate level of PA. PA scores for all domains showed moderate to good reliability across both the 2nd and 3rd trimesters, with ICCs ranging from 0.45 (95%CI: (0.17, 0.64)) for travel PA at 2nd trimester to 0.69 (95%CI: (0.51, 0.80)) for travel PA at 3rd trimester. Agreement for total MVPA was higher in the 3rd trimester compared to 2nd trimester [ICCs 0.62 (0.40, 0.75) vs. 0.55 (0.32, 0.70)], whereas the opposite was true for SB [ICCs 0.48 (0.19, 0.67) vs. 0.64 (0.46, 0.76)]. There was moderate agreement between the GPAQ and accelerometer for total MVPA [ICC=0.55 (0.0, 0.8)] while the agreement between the two was poor for SB [ICC=0.35 (0.0, 0.7)]. Conclusions: The modified GPAQ appears to be a reliable and valid tool for assessing moderate PA, but not SB, among pregnant women in Nepal.