Results
pre-eclampsia, macrosomia, eclampsia, weight gain, GDM, overweight
PRE-ECLAMPSIA, OBESE, POSTPARTUM HEMORRHAGE, ECLAMPSIA, NEONATAL ASPHYXIA, GESTATIONAL HYPERTENSION, GDM, SECONDARY
From March, 2021 to December, 2021, 281 overweight and obese pregnant women were enrolled, among whom 143 participants were assigned to the intervention group and 138 participants were assigned to the control group. 8 and 5 women were lost to follow up respectively in the intervention and control group. The data from 135 women in the intervention group and 133 women in the control group were finally analyzed. The detailed flow chat is shown in Fig. 
the flow chat of the trial
Baseline data of the control group and intervention groupMedian (IQR)
Gestational weight gain of the control group and the intervention groupFor the CS rate, the application of smartphone assisted weight control can significantly reduce it from 65.4% in the control group to 53.3% in the intervention group (P = 0.044, Table 
Primary and secondary outcomes of the control group and intervention group
Primary outcome in overweight and obesity subgroupThe median of adherence to the App is 0.63 (IQR 0.37, 0.78), which is used as a threshold to divide the intervention group into frequent user subgroup (≥ 0.63) and non-frequent user subgroup (< 0.63). There are 66 non-frequent users and 69 frequent users. The median of the GWG of frequent users is 7.5 kg (IQR 5, 10), which is significantly lower than that of non-frequent users is 9.5 kg (IQR 7,11.62, P = 0.014). The CS rate of the frequent user group showed a trend to be lower than that of non-frequent user group (46.38% vs. 60.61%, P = 0.098, Table 
CS in different frequent user subgroupsFor the secondary outcomes, the App intervention can significantly reduce the rate of postpartum hemorrhage from 12.0% in the control group to 5.19% in the intervention group (P = 0.045). However, the differences of gestational hypertension, pre-eclampsia and eclampsia, GDM, neonatal asphyxia, and macrosomia are not significant between the two groups (Table 