Study design and setting
A cross-sectional study with successive recruitment of pregnant women was conducted at two district hospitals in Nepal from May 2016 to May 2017. KIST Teaching Hospital in Lalitpur district is situated in the capital city Kathmandu, whereas Kathmandu University Dhulikhel Hospital (KUDH), in Kavreplanchowk district, is located 30 km northeast from Kathmandu. KIST and KUDH hospitals see about 1200 and 3500 live births each year, respectively.
Pregnant women attending antenatal control at KUDH and KIST hospitals were eligible for inclusion in the study if they were willing to participate, had no history of spinal fracture or surgery, and could understand and speak Nepali. Oral and written consent was obtained from women who agreed to participate in the study. One of two reasearch assistants collected and recorded data on a Samsung tablet with open data kit software.
Ethical approval was obtained from the Norwegian Regional Ethics Committee (REK Nord, 2015/2209), the Nepal Health Research Council Ethical Review Board (112/2016), and the Institutional Review Committee of Kathmandu University School of Medical Sciences/Dhulikhel Hospital (25/16).
Participants completed questionnaires on sociodemographic, pregnancy, and workload characteristics. Sociodemographic information included: age (years), height (cm), weight (kg), ethnicity, women’s and husbands education in years (no education, primary ≤ 5, lower secondary 6–8, secondary 9–10, higher secondary 11–12, bachelor and above ≥ 13), monthly income in United States dollars (USD,$) (no income, less than $76, $76–153, > $153), occupation, marital status (living with husband, husband working away from home, divorced), type of family (nuclear: husband and children; joint: parents-in-law, husband, and children; extended: grandparents, parents-in-law, husband, and children), number of family members, and household work (washing/cleaning/cooking, child care, animal care, fetching water). Pregnancy characteristics included number of pregnancies, parity, and gestation (weeks). Workload information included waking hours, hours of rest during work, types of field work (farming, grass cutting, branch cutting, fetching water), working positions (sitting or squatting, standing or bending forward), and hours of prolonged sitting or standing.
The registration of LBP and PGP was done using a body chart. Participants who reported musculoskeletal pain were asked to indicate the location of their pain on a body chart, which was then validated by having the women point to the site of the pain on their body. If the women pointed to their lower back and/or pelvis, they were considered to have LBP and/or PGP. A physiotherapist then performed further clinical examination on women reporting LBP and/or PGP [7, 24, 25].
The women who reported LBP and/or PGP also responded to questions regarding pain intensity (numeric rating scale, 0 (no pain) to 10 (the most severe pain)) [26, 27], pain frequency (on some days, most days, every day), specific pelvic pain locations (sacrum, sacroiliac joints, and symphysis pubis), whether the LBP and/or PGP limited their usual activities or changed their daily routine for more than 1 day (no/yes) , whether they were concerned about the LBP and/or PGP (numeric rating scale, 0 (not concerned) to 10 (extremely concerned), and whether they believed that the LBP and/or PGP would disappear after delivery (no/yes).
Reliable and valid Nepalese versions of outcome measures were used to assess the severity of activity limitations and symptoms of pregnancy-related LBP and PGP. The Oswestry Disability Index (ODI), version 2 [29, 30], consists of 10 items with scores from 0 to 5, describing an increasing degree of difficulty. The Pelvic Girdle Questionnaire (PGQ) comprises 25 items with scores on a 4-point descriptive scale from 0 to 3, describing an increasing degree of symptoms and activity limitations [31,32,33]. The total sum score for both the ODI and the PGQ is expressed as a percentage from 0 to 100 (severe disability).
The women completed questionnaires on pelvic organ prolapse (POP) symptoms, urinary incontinence (UI), and depression symptoms. The POP symptom score (POP-SS) ranges from 0 to 28, with higher scores indicating more severe symptoms . The International Consultation on Incontinence Questionnaire-UI Short Form (ICIQ-UI SF) score ranges from 0 to 21, with higher scores representing more severe UI symptoms . The short five-item version of the Edinburgh Depression Scale (EDS-5) has four alternative answers to each question, scored from 0 to 3, adding up to a maximum score of 15 to represent the highest severity of depression .
Continuous variables with normal distribution are presented as mean (standard deviation (SD)) or median (interquartile range (iqr), 25th and 75th percentiles) if skewed. Categorical data are presented as numbers and percentages.
To assess the associations between independent variables and LBP and/or PGP, univariate and multivariate logistic regression with odds ratios (OR) and 95% confidence intervals (CIs) were used. The authors planned to include 20 independent variables to assess these associations, requiring at least 200 participants with pregnancy-related LBP and/or PGP. Prior to logistic regression analysis, the independent variables were tested for collinearity, and correlations greater than 0.7 were considered to be one-dimensional. Following this rule, potential univariate associations for 20 independent variables with the outcome of LBP and/or PGP were analyzed using Mann-Whitney U or Chi-square tests, depending on whether variables were continuous or categorical. Variables with p-values less than or equal to 0.25 were included in the multivariate regression model.
In order to enhance interpretability, the variables are presented in the following categories: age: ≤ 21, 22–24, 25–27, ≥ 28 years; weeks of gestation: 1–12, 13–28, 29–40; BMI: < 20, 20–24, 25–30, > 30; education: no education, primary-secondary (5–10 years), higher secondary and above (≥ 11 years); monthly income: no income, ≤ $153, and > $153; child care (no/yes), fetching water (no/yes), field work (no/yes), rest during work (no/yes); POP-SS: no symptoms vs ≥ 3 symptoms of POP (75th percentile); ICIQ-UI SF: no UI or reported UI; and EDS-5: < 5 or ≥ 5 symptoms of depression. A backward strategy was used in the multivariate modelling. Variables with p-values greater than or equal to 0.05 were excluded. Variables in the final model were checked for pair-wise interactions. The Statistical Package for the Social Sciences (SPSS) version 22 was used for statistical analysis.