Proprioceptive, Fear-related and Inflammatory Factors in the Persistence of Pregnancy-related Lumbopelvic Pain.

Pregnancy-related lumbopelvic pain (PLPP) affects 50-90% of pregnant women and is often dismissed as a normal part of pregnancy. However, the long-term consequences can be dramatic. Up to 21% of women with PLPP still have pain three years postpartum, and 10% experience disability, poorer quality of life, and lower ability to work 11 years after delivery. Because the multifactorial etiology of PLPP is unclear, prevention and treatment fall short. Previous studies on the causes of PLPP focused on impairments in motor output but ignored that impairments in sensory input (e.g., proprioception, the primary expertise of our research group) often precede motor output problems. Moreover, though psychological factors such as fear (of movement) are known to affect PLPP, their predictive role in PLPP remains understudied. Finally, the role of systemic inflammation in PLPP has yet to be examined, despite recent studies demonstrating its role in the chronification of lumbopelvic pain in the general population.

This prospective cohort study aims to identify new modifiable predictors for the onset of PLPP during pregnancy and its persistence postpartum. The investigators will compare sensory (proprioception, body perception), fear-related, and inflammatory factors between women with and without PLPP and determine their predictive role in the onset and persistence of PLPP. The results will increase our understanding of the multifactorial etiology of PLPP and help optimize prevention and treatment.

This study comprises a prospective cohort study with three objectives.

Objective 1 is to investigate whether the reliance on lumbar versus ankle proprioception during standing and body perception at the lower back (i.e., "proprioceptive factors"), anxiety, fear of movement, pain catastrophizing, depression, stress, and coping with stressful situations (i.e. "fear-related factors"), and inflammatory markers (i.e., "inflammatory factors") change over time and differ between women with and without PLPP in the 3rd pregnancy trimester, 6 weeks postpartum, and 9 months postpartum. We hypothesize that women with PLPP show (1a) a maladaptive reliance on ankle proprioception and/or disturbed body perception at the lower back, (1b) higher levels of fear of movement, anxiety, stress, depression, pain catastrophizing and poorer coping with stress, and (1c) greater immune activation and a disturbed balance of pro- vs. anti-inflammatory markers compared to pain-free women.

Objective 2 is to determine whether the proprioceptive, fear-related, and inflammatory factors are correlated in women with PLPP. Based on previous findings (52-55), we hypothesize that anxiety correlates with higher concentrations of IL-6 and IL-12, and lower concentrations of IL-2 and IL-10. We will also examine whether maladaptive reliance on ankle proprioception and disturbed body perception at the lower back correlate with fear of movement, anxiety, and concentrations of inflammatory markers in women with PLPP.

Objective 3 (= primary objective) is to investigate whether the proprioceptive, fear-related, and inflammatory factors predict the presence of PLPP in the 3rd trimester, 6 weeks postpartum and 9 months postpartum. Based on (our own) research (20,26,33,38,39,56), we hypothesize that a maladaptive reliance on ankle proprioception and disturbed body perception at the lower back, higher levels of anxiety and fear of movement, and immune activation and disturbed balance of pro- and anti-inflammatory markers in the 1st trimester predict having PLPP in the 3rd trimester. We also expect that the presence of these factors in the 3rd trimester predicts the persistence of PLPP 6 weeks and 9 months postpartum.

Eligibility Criteria:
Inclusion Criteria:

* Informed consent to participate
* 18-40 years old
* First pregnancy
* Singleton pregnancy (confirmed through ultrasound)
* No current PLPP
* Dutch- or English speaking

Exclusion Criteria:

* Pregnant for more than 16 weeks
* Currently experiencing PLPP, or having had PLPP during the index pregnancy
* History of surgery or major trauma to spine, pelvis or legs
* Specific vestibular or balance disorders
* Use of medication that could affect balance (e.g., ototoxic or centrally-acting drugs)
* Specific spinal conditions or deformities (e.g., structural scoliosis)
* Rheumatic disease
* (History of) a neurological disorder (e.g., neuropathy)
* Problems with vision that are not corrected by glasses, contact lenses or surgical eye correction
* Hyperemesis gravidarum
* Recent history of ankle problem (e.g., ankle sprain less than 3 weeks ago)
* Currently having a condition that may compromise the normal course of the pregnancy (e.g., hypertension, renal disease, coagulation disorder)
* Use of corticosteroids or NSAIDs
* (History of) endocrine, nutritional, metabolic, inflammatory, (auto)immune, cardiovascular conditions, or cancer
* Comorbidities that might influence inflammatory markers (e.g., acute illness, infection (e.g. CMV, HPV, urinary tract infection...), hypothyroidism, endometriosis)
* (History of) psychiatric disorder