Pregnancy‐related pelvic girdle pain

Abstract

In April 2007, van de Pol et al. reported their findings on pregnancy-related pelvic girdle pain based on results from their cohort study (n = 412) in which pelvic floor problems, sexuality and back and pelvic girdle pain during first pregnancy up to 1 year after delivery were assessed 1. Although the authors stated that prevalence rates on pregnancy-related pelvic girdle and/or low back pain are not available in a healthy pregnant population in the Netherlands, data are available from a large longitudinal, prospective cohort study (n = 7526), where the prevalence, etiology, severity and prognosis of pregnancy-related low back and/or pelvic girdle pain was studied during pregnancy until one year after delivery 2-4. Midwives and gynecologists recruited the women during early pregnancy (14 weeks) between November 2000 and November 2002. Follow-up measurements were at 30 weeks gestation, two weeks after delivery, six and 12 months after delivery. Prevalence rates of pregnancy-related pelvic girdle and/or low back pain for women with a history of pain were 88.5% during pregnancy and for women without a history 67.4%. Prevalence dropped significantly two weeks after delivery to 53.8% for women with a history and to 28.1% for women without a history. Figures for the whole group stabilized in the year after delivery to 35% at one year after delivery. However, these figures provide no insight into the severity of pain nor into limitation in activities and/or restriction in communal or social participation 1-3. We support the authors’ assertion that the estimation of prevalence rates of pregnancy-related pelvic girdle pain is complicated and such assessment is sensitive to terminology, definitions and study population. We would like to comment, however, on the way the prevalence data were collected by van de Pol et al. and some underlying assumptions of their study. The authors prefer the term “pregnancy-related pelvic girdle pain” because it does not suggest a specific etiology. We agree with that. Nevertheless, the authors used the term “pelvic instability” during the data collection because they assumed that this term has come to mean the same thing in the Netherlands. Prevalence was assessed with the question: “Do you think you suffer from pelvic instability?”. Additionally, the authors asked: “Do you suffer from back and/or pelvic pain at the present time?” and asked the women thereupon to indicate the location of the pain on a drawing. Only the women who indicated pain in the back (including the lower back) were considered as having back pain. Authors in this research field often hypothesize that there is a distinction between pregnancy-related pelvic girdle and lumbar pain. Based on that it is assumed that pelvic girdle and lumbar pain have different etiology. But as the authors of this article themselves stated, the etiology of the pregnancy-related pain in the lumbo-pelvic region is still largely unknown. It is not clear why the authors make the distinction between “pelvic instability” and “back pain” in the data collection and presentation of the data. Prevalence figures in the results section showed very low rates of pelvic instability (7.0% de novo during pregnancy) and back pain (every second pregnant woman) in comparison to several other studies including our study (77–84%) 2. The very low prevalence rates by van de Pol et al. could have been caused by the introduction of the term “pelvic instability” in the data collection. Pelvic instability is an emotionally charged term that some women and caregivers in the Netherlands embrace as a definable clinical entity and others not. Additionally, the style of the question seems important. The women should be invited to list presence or absence of pain in the pelvic girdle and the lower back and the beginning of the pain in a neutral way. The style of the question “do you think you suffer from … … .” refers to pain beliefs. Pain beliefs reflect the patient's own ideas about what pain is and what it means to them. The question whether a woman thinks she suffers from pelvic instability probably measures quite a different phenomenon than the intended purpose: the prevalence of pregnancy-related pain in the pelvic girdle or back. Results of other collected variables, such as limitations in physical activity, return to work and psychosocial variables in this particular group of patients, underpin the suggestion that this is a highly selective group with a high burden of suffering and not representative of a population of healthy women with some form of pregnancy-related pain in the pelvic girdle and/or the lumbar region during pregnancy or in the first year after delivery. Finally, the authors introduced a new questionnaire to measure limitations in activities for this group of women. The questionnaire (Pregnancy Mobility Index) was developed by the authors at an earlier stage. Unfortunately, the authors decided not to use a second instrument to measure disability like the RDQ-24 (Roland Disability Questionnaire, Dutch validated version) in their study. The Pregnancy Mobility Index is not validated against the RDQ. Better standardization of outcome measurements facilitates comparison of results among different studies. The RDQ is already investigated in various populations with different aspects of low back pain. Measurement properties of the scale were always satisfactory. The scale is easy to modify to the specific group of patients by adding the statement: “Because of my back including the pelvic girdle” to each item instead of the original statement: “Because of my back”.