Characteristics of study population
The characteristics of study participants are shown in Table 1 . The mean age of 908 pregnant women was 31.8 ± 3.9 years. The mean height was 162.94 ± 4.98 cm. The mean pre-pregnancy weight was 59.18 ± 10.01 kg. The mean final weight was 71.43 ± 10.17 kg. The mean GWG between the first visit and the fourth visit was 12.57 ± 4.92 kg. The mean pre-BMI was 22.37 ± 3.37 kg/m2, among which about 8.3% of the participants were stratified as low weight for pre-BMI < 18.5kg/m2, 64.0% had normal pre-BMI, and 27.7% were stratified as overweight and obese for pre-BMI ≥ 24.0kg/m2. 233 pregnant women suffered from GDM as the incidence was 25.7%, which can be ascribed to the relatively higher mean age. 45.0% of the participants were pregnant for the first time. 66.4% of the participants were primiparas and 33.6% were multiparas. The mean gestational age was 39.3 ± 1.4 weeks.