During pregnancy, women often experience musculoskeletal pain, specifically in their low back and/or pelvic girdle. Pelvic girdle pain (PGP) is defined as pain between the posterior iliac crest and gluteal fold, particularly in the region of the sacroiliac joint (SIJ)1. Although it is often referred to as "sciatica". PGP in pregnancy is common with prevalence estimates of 45%2. Previous studies have found that one third of patients will rate their PGP intensity as severe, leading to functional impairments. Functional disabilities include sitting, walking, and standing; thus, significantly impacting the ability of patients to perform routine daily activities. This pain has been reported to develop as early as 17-19 weeks' gestation, lasting up to 3 months postpartum; with a peak incidence of 24-36 weeks.

The etiology of PGP in pregnant women is still not fully understood, largely due to the complex interactions between bone, ligaments, fascia, and muscles in the pelvic joints3. Some studies suggest the increased mobility of the joints in the pelvic girdle during pregnancy due to relaxing cause a lack of stabilization in the sacroiliac region, which results in pain4. Thus, it is hypothesized that providing stabilization of the joints with an external force, such as a maternity or SIJ belt, will improve pain.

During pregnancy, women often experience musculoskeletal pain, specifically in their low back and/or pelvic girdle. Pelvic girdle pain (PGP) is defined as pain between the posterior iliac crest and gluteal fold, particularly in the region of the sacroiliac joint (SIJ)1. Although it is often referred to as "sciatica". PGP in pregnancy is common with prevalence estimates of 45%2. Previous studies have found that one third of patients will rate their PGP intensity as severe, leading to functional impairments. Functional disabilities include sitting, walking, and standing; thus, significantly impacting the ability of patients to perform routine daily activities. This pain has been reported to develop as early as 17-19 weeks' gestation, lasting up to 3 months postpartum; with a peak incidence of 24-36 weeks.

The etiology of PGP in pregnant women is still not fully understood, largely due to the complex interactions between bone, ligaments, fascia, and muscles in the pelvic joints3. Some studies suggest the increased mobility of the joints in the pelvic girdle during pregnancy due to relaxing cause a lack of stabilization in the sacroiliac region, which results in pain4. Thus, it is hypothesized that providing stabilization of the joints with an external force, such as a maternity or SIJ belt, will improve pain.

Clinically, pelvic belts are often used as a part of a multimodal approach to reduce PGP alongside other conservative treatments such as analgesics and physical therapy, or more alternative treatments such as acupuncture5. This makes it difficult to determine their individual effect on pain reduction. Further confounding this issue are variations in physician counseling, physical therapy regimens, and analgesic usage. Moreover, several support belts have been designed that vary in padding size, flexibility, and site of application5-7. Among these belts, it has not yet been identified which belt is most beneficial regarding pain reduction and patient tolerance5. Previous studies have found benefit in short term use (3-6 weeks) of maternity belts, providing women with improved pain and function compared to exercise or no intervention7. Pelvic belts are a cost-effective option to treating PGP, and more specifically SIJ pain, yet studies are limited regarding the effect they have on SIJ mobility and pain reduction8 and more specifically determining what clinically predicts those who will benefit most from an SIJ belt.

The active straight leg raise test originally described by Mens is an examination maneuver that measures functional mobility and has been correlated with pregnancy related PGP (cite). Anecdotally, our clinical team has observed that women who benefit from compression during the second part of the test, seem to benefit most from the use of an SIJ belt. Having a simple test for obstetric providers to perform in pregnant women with pain would be informative in determining who might benefit most from an SIJ belt. Hence our study seeks to investigate the following aims:

Inclusion Criteria:

• English speaking pregnant women presenting in their second or third trimester with posterior PGP. Trimester will be determined from date of last menses or ultrasound date.
• Pain must be between the upper level of the iliac crests and the gluteal folds in conjunction with or separately from pain in the pubic symphysis and influenced by position and locomotion
• ASLR score between 2-10

Exclusion Criteria:

• Non-English speaking pregnant women <18 or >50 years old
• Women presenting with PGP in the first trimester (<13 weeks gestation)
• Women with pubic symphysis (anterior) pain alone
• Pain above the upper level of the iliac crest
• ASLR total score of <2
• History of lumbar or pelvic fracture, neoplasm, inflammatory disease, active urogenital infection or active gastrointestinal illness, previous surgery of the lumbar spine, pelvic girdle, hip joint or femur
• History or signs of radiculopathy or other systemic neurologic disease

Adverse event data were collected for six weeks

There are no limitations or caveats to report.