Normal width of the inter-recti distance in pregnant and postpartum primiparous women

Study Design: Longitudinal descriptive exploratory study. Objectives: Evaluate the normal width of the linea alba in first-time pregnant women during pregnancy and postpartum. Background: There are normative values on the width of the linea alba for nulliparous women, but limited knowledge about the normal width of the inter-rectus distance (IRD) in pregnant and postpartum women. Methods: Ultrasound images were recorded in 84 primiparous women, at 3 locations on the linea alba (2 cm below the umbilicus, and 2 and 5 cm above the umbilicus) and at 4 time points (gestational weeks 35-41 and 6th to 8th, 12th to 14th, and 24th to 26th weeks postpartum). The 20th and 80th percentiles were used to define the normal width of the linea alba. Results: During pregnancy, the 20th and the 80th percentile corresponded to 49-79mm below the umbilicus, 54-86 mm at 2 cm above the umbilicus and 44-79 mm at 5 cm above the umbilicus. At 6 months postpartum, the 20th and the 80th percentile corresponded to 9-21 mm at 2 cm below the umbilicus, from 17 to 28 mm at 2 cm above the umbilicus and from 12 to 24 mm at 5 cm above the umbilicus. Conclusion: Different normative values for the width of the linea alba were found at different locations of the anterior abdominal wall. In primiparous women, the IRD may be considered normal up to values wider than in nulliparous.