Background: Over the past decade there have been rapid advancements in telemedicine and mobile health technology (mHealth) and rapid increases in adoption of these technologies among OB-GYN providers. Mobile technology is routinely used in the general adult population to simplify monitoring of food intake and weight. Studies have demonstrated that weight loss achieved via remote monitoring, through use of wi-fi scales and web applications, is similar to weight loss achieved with in-person support. These technologies also increase flexibility for subjects and providers. However, there has been limited large-scale research to evaluate the use of these technologies to improve adherence to weight-gain recommendations during pregnancy. Objectives: To evaluate gestational weight gain tracking in a large low-risk obstetrical population using remote patient monitoring and a mobile phone app. Methods: Self-reported age, height, estimated due date, and weight data were extracted from low-risk, singleton pregnancies entered from 50,769 participants who were enrolled in the BabyScripts TM phone app between 1 January 2016 and 1 March 2020. After data cleaning, 15,468 participants were included the final analysis. Linear regression and Spearman's correlation were used to examine the relationships between total weight gain, rate of weight gain, body mass index (BMI), postpartum weight loss, and app engagement. Results: The average weight gain in the first, second, and third trimester were 0.09 ± 1.8 kg, 4.2 ± 3.3 kg, and 3.9 ± 3.9 kg, respectively. The average rate of weight gain per week for the second and third trimesters were 0.5 ± 0.4 kg/wk and 0.6 ± 0.8 kg/wk, respectively. Participants with higher initial BMI had slower rate of weight gain than those with lower initial BMI (r = -0.24, r = -0.05, for second and third trimester, respectively). Overall, 21.4% of participants met the Institutes of Medicine (IOM) recommendation for total weight gain during pregnancy. Patients who were highly engaged with the mobile app had increased adherence to the IOM guidelines (29.8% vs. 9.4%, p < 0.001). A larger proportion of highly engaged patients adhered to the IOM guidelines for rate of weight gain in the second and third trimester, compared to the lowest engaged patients (12.7% vs. 6.8%, p < 0.001). On average, participants lost 8.8 ± 3.3 kg over an average of 8.1 ± 4.6 weeks in the immediate postpartum period. This weight loss was positively associated with engagement (r = 0.3, p < 0.001). Comments: Engagement with the mobile app was associated with increased adherence to the IOM gestational weight gain guidelines and with increased postpartum weight loss. Use of remote patient monitoring in conjunction with mHealth technology may be a strategy to improve adherence to IOM guidelines.