Differences in Inter-Rectus Distance and Abdominopelvic Function between Nulliparous, Primiparous and Multiparous Women

Abstract

Widening of the inter-rectus distance (IRD) is highly prevalent among postpartum women and can lead to dysfunction of abdominopelvic muscles. The aim of this study was to evaluate the differences in IRD and abdominopelvic function between nulliparous, primiparous and multiparous women. A cross-sectional study was conducted on 75 women (25 nulliparous, 25 primiparous and 25 multiparous at 6 months postpartum). The participants underwent ultrasound assessment under three conditions (at rest, abdominal draw-in maneuver (ADIM) and curl-up) at two locations (2 cm above and 2 cm below the umbilicus). Furthermore, abdominopelvic muscle function was determined by prone, supine and side bridge tests. In all conditions and locations, the IRD were significantly higher (p < 0.05) in the primiparous and multiparous women than in the nulliparous. The multiparous women presented greater (p > 0.05) IRD at rest and during ADIM compared to the primiparous women. Regarding abdominopelvic muscle function, differences were only significant (p < 0.05) between the nulliparous with primiparous women in prone and supine conditions. These findings suggest that parity influences IRD: women at 6 months postpartum present greater IRD compared to nulliparous women; multiparous women present greater IRD at rest and during the activation of deep abdominal muscles than primiparous women; and primiparous women exhibit worse abdominopelvic muscle function than nulliparous women.

Dynamic Evaluation of the Rectus Abdominis Muscle before and after Delivery by Ultrasonography

“…ese results suggest that the inter-rectus distance can directly reflect the situation of DRA, and has an effect on the rectus abdominis at umbilical level. Under the action of estrogen and progesterone, the collagen fibers of pregnant women will gradually expand and stretch, weakening their muscle strength to meet the needs of delivery, while the gradually enlarging fetus and uterus will press pelvic floor muscle tissue and rectus abdominis for a long time, resulting in the damage of muscle tissue, blood vessels, and nerve, and destroying the support system of their abdominal and pelvic organs [22][23][24]. On the other hand, due to the over extension of the abdominal muscles, the mechanical vector decreases, the position of the white line of the rectus abdominis on both sides is separated, the distance between the rectus abdominis increases abnormally, the strength and support function of abdominal muscle weaken, and other adjacent muscle groups are overloaded, resulting in low back pain, lower stability of the pelvic floor structure, and even displacement of pelvic and abdominal organ in severe cases [25][26][27].…”

Technical aspects of inter-recti distance measurement with ultrasonographic imaging for physiotherapy purposes: the scoping review

“…All 49 included publications (published between 2008 and August 2022) were related to physiotherapy or physical exercise/training and described IRD measurements using USI. Eight studies were from Canada [8,17,20,33,48,[53][54][55] and nine from Spain [11,[42][43][44][45][56][57][58][59]. Countries with two studies were Brazil [60,61], the USA [9,62], the UK [16,63], Norway [13,37], New Zealand [47,64], and China [65,66].…”

“…Of the 27 studies that examined IRD during specific muscle activity/task in supine, some used more than one task. The tasks were head lift [8,13,48,53,55], trunk flexion with scapulae raised fully or partially off the coach (referred to as trunk flexion [60,61], partial curl-up [9,47,62], semi curl-up [8,74], curl-up [13,27,34,56,64,70], abdominal crunch [11,35,36,49,71,73], modified abdominal sit-up [67], and abdominal contraction [56]), transversus abdominis contraction/abdominal drawing-in maneuver (ADIM) [13,35,37,49,56,58,73,74], curl-up/abdominal crunch with preactivated transversus abdominis (by ADIM [11,73,74] or pelvic floor muscles (PFM) contraction [34]), exclusive PFM contraction [13,37], combined PFM contraction and curl-up [13], combined PFM contraction and ADIM [13,37,64]…”

Reference Data on the Normal Abdominal Wall Anatomy and Baseline Characteristics in Seventy-One Nulliparous Women

“…Beer et al assessed 150 nulliparous women with ultrasound in a supine position and measured the IRD at three different points ( 5 ). Balasch-Bernat et al included 75 women, of whom 25 were nulliparous, in their measurement of the IRD ( 7 ). Tuominen et al compared the IRD in nulliparous, with postpartum women ( 8 ).…”