Pain status
The overall aim of this study was to identify the prevalence of persistent PLBP and PGP at 12 months postpartum as well as difference over time, evaluating pain status, SRH and current family situation. A significant finding in this present study was an increased probability of ‘recurrent pain’ and ‘continuous pain’ compared to women with ‘no pain’ at Q3 if a woman had experienced LBP before the pregnancy, thus confirming previous findings [
20,
28]. The most commonly reported pain characters in this study were dull, stabbing and cutting pain, where dull pain seems to be the most common pain character both in women reporting ‘recurrent’ and ‘continuous’ pain at both Q2 and Q3. Previous studies have also shown that these pain characteristics are the most commonly reported among women with PLBP/PGP [
3,
29]. Women with ‘continuous pain’ at Q3 reported statistically significant higher level of pain compared to women with ‘no pain’ at Q3 at all measured time points, while women with ‘recurrent pain’ (Q3) reported statistically significant higher levels of pain compared to the ‘no pain’ group the past 6 months as well as the past week at Q3. These results were somewhat expected, as it make sense that individuals with recurrent or continuous pain would also report higher levels of pain compared to individuals with no pain at approximately 14 months postpartum. Noteworthy is that pain status appears to change over time but that localisation does not seem to change in the majority of women reporting continuous pain. Few women with continuous pain at Q2 report full remission of symptoms at Q3.
Self-rated health (SRH)
It is well established that poor SRH is related to pain [
30] and reduced SRH may influence LBP [
31]. In a prospective study, Svedberg et al. [
32] have found that back pain contributed to poor SRH [
32]. This study showed that there was a statistically significant difference in regard to SRH between the ‘recurrent pain’ and the ‘continuous pain’ group (categorized at Q3) during pregnancy (Q1) and during the first 6 months postpartum (Q2), where the ‘continuous pain’ group (Q3) seemed to report a less favourably health status. Also, there was an increased likelihood that women with ‘continuous pain’ assessed their health status as ‘poor or quite poor’ compared to women with ‘recurrent pain’ at Q3.
Relationship satisfaction
Social support has shown to be favourable for both health and welfare, particularly beneficial is marriage satisfaction [
33]. For example, research has shown an association between marriage and morbidity and mortality benefits where mortality rates are much higher in unmarried women than for married [
33]. In our study, the results show a stable relationship satisfaction throughout the three subgroups, where the majority of individuals rated their relationship satisfaction as ‘good’ or ‘very good’. A study by Albert et al. [
28] did not show any difference between groups with or without PGP in regard to marital status. This could possibly be due to the fact that having a baby is usually considered a positive life event and thus have a strengthening effect on the relationship. The vast majority of the women in the study were married or cohabiting. Most women reported a relationship satisfaction of ‘good’ to ‘very good’. There were no differences between the three different subgroups (Q3) at either of measured time points, which indicated a stable relationship satisfaction. Interestingly, a statistically significant difference in relationship satisfaction was shown between respondents and non-respondents, with a less positive scoring regarding relationship satisfaction among the non-respondents in this study.
General discussion
The findings in this study regarding pain are congruent with research concerning both NSLBP and PLBP/PGP, where recurrence of LBP and PLBP/PGP is strongly correlated with previous episodes of LBP [
11‐
15,
20,
28]. In addition, previous research in the non-pregnant general population shows that an increase in duration of an episode of LBP and/or persistence is a strong predictor of poor outcome [
34,
35]. Bothersomeness and psychosocial measures have also been found to be a valid measure of severity in LBP [
36] and there appears to be an accumulation of risk over time for pain itself [
37].
It has been suggested that PLBP/PGP is to be considered a ‘normal condition’ of pregnancy [
24,
38] and PGP has been explained by early menarche [
39], biomechanical dysfunction in the pelvic joints due to hormonal and postural changes during pregnancy [
1,
40,
41]. Nevertheless, these findings are inconclusive.
Numerous women suffering from PLBP/PGP experience difficulties performing normal daily activities such as prolonged sitting and/or getting up from a sitting position, turning over in bed, dressing/undressing, walking, lifting and carrying small weights [
9,
42]. Also, women with PGP seem to be more afflicted than women with PLBP [
8,
16,
43] and some may become so incapacitated to the extent that there is a need to use crutches and/or wheelchairs [
2,
9]. Many women also experience sexual difficulties due to the pain. We have previously reported that 7/10 women with PLBP/PGP are more likely to have an unsatisfying sexual life during pregnancy compared with women without pain [
10]. So when taking into account the decreased functional status of many women suffering from PLBP/PGP and that the life-time prevalence of LBP in Swedish women has been estimated to 66% [
23], and that the prevalence of PLBP/PGP during pregnancy is even higher (72%) [
20], this condition must instead be considered a complication of pregnancy and a major health issue among women in childbearing age.
The results in this study revealed that a spontaneous full recovery with no recurrences of symptoms seems to be an unlikely course for some women suffering from PLBP/PGP, very much like for most non-pregnant individuals [
44,
45]. Further, this study shows that pain status appears to change over time and for some women the condition is not self-limiting. Instead, 142 out of 176 women (almost 80%) responding to Q3 reported recurrent or continuous pain 14 months postpartum, constituting a prevalence of persistent pain of 22% from the initial cohort (n = 639). These findings can be compared in the light of the research by Norén et al. [
18] that observed that 5% of all pregnant women, or 20% of pregnant women with LBP during pregnancy, still experience symptoms three years postpartum [
18]. Furthermore, recent research shows that a large proportion of non-pregnant individuals in the general population suffering from LBP, still experiences pain one year after an episode of pain and a majority experiences recurrent pain [
11,
45]. Hence, LBP can no longer be seen as a self-limiting condition in neither the non-pregnant general population nor in women affected with PLBP/PGP.
A long-standing top priority has been to establish more homogenous subgroups of patients suffering from LBP and several attempts have been made to do so (i.e. subgrouping based on pain severity and psychosocial characters). Lately, several researchers have focused on different trajectories in the natural and clinical course of LBP to enable the identification of clinically meaningful subpopulations [
46‐
49]. The result in this study suggests that women suffering from recurrent or continuous PLBP/PGP may very well constitute a specific prognostic category of patients, even though further research is needed. Additionally, women with recurrent or continuous PLBP/PGP postpartum may also need earlier interventions and more specific treatment regime for better management of their symptoms, as a more conservative pain management approach may be counterproductive in regard to symptomatology.
In the field of LBP research, predictors of poor outcome has shown to be, but not limited to, high pain intensity, long duration, distress, low self-efficacy and previous LBP [
50,
51]. Low scores regarding SRH may also influence LBP [
31]. However, there is one risk factor that has been suggested to be of particular importance and that is previous episodes of LBP [
52] and this is also true for PLBP and/or PGP [
1,
2,
53]. This study confirms previous findings by demonstrating that women who have experienced LBP before their pregnancy had an increased likelihood of experiencing recurrent or continuous pain 14 months postpartum. Furthermore, women with ‘continuous pain’ experienced statistically significant higher levels of pain at all measured time points compared to ‘no pain’ and the ‘recurrent pain’ group.
Methodological considerations
There are some methodological considerations in this study that should be acknowledged. Today, PGP is defined in accordance with positive diagnostic tests as well as pain upon palpation of the ligaments and joints of the pelvis [
1] and the pain can be continuous or recurrent. However, this study commenced in 2002 and at that point in time the above definition was not available. Instead pain drawings were used to describe pain location [
20]. PGP has often been identified and confirmed by self-rated pain location and/or in combination with clinical tests [
6,
8,
9] and PLBP and PGP can be distinguished from each other through pain locations and clinical examinations [
8]. However, lumbar pain symptoms could not be excluded in this study since pain sites correlates with common anatomical location of LBP. Nevertheless, the prevalence of LBP are considered stable, while pelvic pain increases [
54] during pregnancy, thus determinants and outcomes are mostly related to pregnancy-related pelvic pain [
21].
A five category alternative is commonly used regarding questions concerning SRH to improve the ability to differentiate self-rated health status among people. However, response alternatives seem to differ between studies [
30,
32,
55,
56]. Svedberg et al. [
32] used the response alternatives ‘excellent’ , ‘good’ , ‘moderate’ , ‘fairly poor’ , and ‘poor’ while the Swedish National Institute of Public Health use the response alternatives ‘very good’ , ‘good’ , ‘fair’ , ‘bad’ , and ‘very bad’. This could be considered a limitation in this study. Nevertheless, studies using similar response alternatives as in this present study found strong correlations between poor SRH and mortality [
55,
56], which may indicate that the results regarding SRH in this study is reliable.
The validation of the data in this study has previously been discussed at length [
20]. Briefly, the non-respondents did not differ from respondents in regard to maternal age, gestational age, birth weight, mode of delivery, total experience of delivery, epidural or spinal anaesthesia during delivery, and pre-pregnancy or end-pregnancy BMI at Q1. The conclusion was that the data collected through Q1 seem to be representative for women with persistent LBP and/or PGP postpartum. Even though this study is a long-term follow-up study based on a previous cohort study, questions in Q2 and Q3 was similar from those in Q1. In addition, there seem to be no difference between the respondent and non-respondents in regard to base line variables (with the exception of smoking and maternal age at first delivery). Therefore, the data seem to be representative for Swedish women with recurrent or continuous LBP and/or PGP 14 months postpartum.
As with all musculoskeletal pain, psychosocial factors appear to exacerbate the clinical component of pain [
57,
58]. In addition, a study has shown that postpartum depressive symptoms are three times more prevalent in women with lumbopelvic pain compared to those without [
59]. However, the material in this study did not contain information in regard to psychosocial factors (such as self-efficacy, distress, depression and fear-avoidance beliefs) apart from relationship satisfaction and family situation, which are in and by itself a limitation.
Clinical implications
PLBP/PGP constitutes a significant health problem for many women during and after pregnancy. The main findings in this study suggest that PLBP/PGP is not only a major health problem among women 14 months postpartum, negatively affecting their SRH, but also a major public health issue. In general, women reporting ‘continuous pain’ reported poorer SRH compared both to women with ‘recurrent pain’ as well as ‘no pain’. In addition, women with ‘continuous pain’ reported more of a dull pain at both Q2 and Q3 compared to women with ‘recurrent pain’ and most women with ‘continuous pain’ reported no change of the localisation of pain. This may indicate that there is a difference among women who reported PLBP/PGP during pregnancy regarding the long term clinical outcome and that for some of these women the long-term outcome is less favourable. Thus, screening women with risk factors for postpartum PLBP/PGP, such as previous LBP, need to be considered early in the pregnancy. This to enable clinicians to provide better pain management, such as i.e. pelvic belt [
60], referral to acupuncture and stabilizing exercises [
61], and chiropractic care [
17,
62] but also to facilitate a more realistic view regarding the prognosis of recurrent and continuous PLBP/PGP postpartum.