Objective To evaluate the incidence and severity of diastasis recti abdominis (DRA) in parturients at the 42-day postpartum and analyze the maternal and infant risk factors associated with postpartum DRA occurrence using a two-step method with conventional two-dimensional ultrasonography. Methods Postpartum women (consecutive cases) who delivered at our hospital and underwent the 42-day postpartum checkups between September and October 2022 were included in this study. All enrolled women first performed curl-up movement under the guidance of a sonographer, and the boundaries of the rectus abdominis were located in the contracted state using conventional two-dimensional ultrasound (first step). Then, the parturients were instructed to lie supine in a relaxed state of rectus abdominis to measure the inter-rectus distances (IRD) (second step). The IRD was measured at three locations: 3 cm above the umbilicus, at the level of the umbilicus, and 3 cm below the umbilicus. The diagnosis of DRA was established and classified into mild, moderate, and severe groups according to the guidelines of the European Hernia Society for DRA management. The incidence of DRA and the proportion of mild, moderate, and severe cases were statistically analyzed. Maternal information (including age) and infant information (including birth weight) were recorded. Statistical analysis was conducted to examine the relationships of these maternal and infant factors with the occurrence and severity of DRA. Results A total of 400 parturients were enrolled in this study. The incidence of DRA was 81.75% (327/400), including 171 cases of mild DRA (52.29%), 152 cases of mode-rate DRA (46.48%), and 4 cases of severe DRA (1.22%). Compared with the non-DRA group, the DRA group had higher neonatal birth weight (3 385 g vs. 3 190 g, P<0.001), a higher rate of cesarean section (114/327 vs. 13/73, P=0.005), and a higher proportion of women with parity >1 (89/327 vs. 11/73, P=0.030). No statistically significant differences were observed for other maternal or infant factors between the two groups. Binary logistic regression analysis showed that higher neonatal birth weight, cesarean section, and higher parity were independent risk factors for DRA (OR: 1.001, 2.549, and 2.053, respectively). Compared with the mild DRA group, the moderate DRA group had higher neonatal birth weight (3 401 g vs. 3 370 g, P=0.036), a higher rate of cesarean section (70/152 vs. 42/171, P<0.001), a higher proportion of women with parity greater than 1 (49/152 vs. 36/171, P=0.030), and a higher pre-delivery body mass index (BMI) (26 vs. 25, P=0.023). No statistically significant differences were observed for other parameters between the two groups. Conclusions The incidence of DRA among postpartum women is relatively high, with nearly half of the cases being moderate or severe, respectively. The two-step method using conventional two-dimensional ultrasonography is of significant clinical value for the timely detection of abnormalities. It facilitates the provision of timely and precise postpartum rehabilitation guidance tailored to different severity levels. Furthermore, this two-step method offers the advantages of simpler and more accurate delineation of the borders of the rectus abdominis. Maternal and infant risk factors, including neonatal birth weight, cesa-rean section, parity, and pre-delivery maternal BMI, affect the occurrence and severity of postpartum DRA.