Abstract
STUDY QUESTION
Is pre-pregnancy hormonal contraception use associated with the development of pelvic girdle pain during pregnancy?
SUMMARY ANSWER
In contrast to combined oral contraceptive pills, long lifetime exposure to progestin-only contraceptive pills or the use of a progestin intrauterine device during the final year before pregnancy were associated with pelvic girdle pain.
WHAT IS ALREADY KNOWN
Pelvic girdle pain severely affects many women during pregnancy. Smaller studies have suggested that hormonal contraceptive use is involved in the underlying mechanisms, but evidence is inconclusive.
STUDY DESIGN, SIZE, DURATION
A population study during the years 1999–2008.
PARTICIPANTS/MATERIALS, SETTING, METHODS
A total of 91 721 pregnancies included in the Norwegian Mother and Child Cohort Study. Data were obtained by two self-administered questionnaires during pregnancy weeks 17 and 30.
MAIN RESULTS AND THE ROLE OF CHANCE
Pelvic girdle pain was present in 12.9% of women who had used combined oral contraceptive pills during the last pre-pregnancy year, 16.4% of women who had used progestin-only contraceptive pills, 16.7% of women who had progestin injections and 20.7% of women who had used progestin intrauterine devices, compared with 15.3% of women who did not report use of hormonal contraceptives. After adjustment for other study factors, the use of a progestin intrauterine device was the only factor based on the preceding year associated with pelvic girdle pain [adjusted odds ratios (OR) 1.20; 95% confidence interval (CI): 1.11–1.31]. Long lifetime exposure to progestin-only contraceptive pills was also associated with pelvic girdle pain (adjusted OR 1.49; 95% CI: 1.01–2.20).
LIMITATIONS, REASONS FOR CAUTION
The participation rate was 38.5%. However, a recent study on the potential biases of skewed selection in the Norwegian Mother and Child Cohort Study found the prevalence estimates but not the exposure-outcome associations to be influenced by the selection.
WIDER IMPLICATIONS OF THE FINDINGS
The results suggest that combined oral contraceptives can be used without fear of developing pelvic girdle pain during pregnancy. However, the influence of progestin intrauterine devices and long-term exposure to progestin-only contraceptive pills requires further study.
STUDY FUNDING/COMPETING INTEREST(S)
The present study was supported by the Norwegian Research Council. None of the authors has a conflict of interest.
Keywords: hormonal contraception, pelvic girdle pain, pregnancy, risk factors, the Norwegian Mother and Child Cohort Study
Introduction
One in five pregnant women experience pelvic girdle pain during pregnancy (Vleeming et al., 2008). The pain frequently results in functional disabilities such as difficulty walking, and the condition is a major cause of sick leave during pregnancy (Robinson et al., 2006). In some women, disabling pain may persist years after delivery (Vleeming et al., 2008). Yet the causes of pelvic girdle pain remain unclear. Because pelvic girdle pain often occurs during the early stages of pregnancy (Kristiansson et al., 1996) and the symptoms typically regress shortly after delivery (Bjelland et al., 2013), endogenous hormonal factors are likely to play a role. Although it has been suggested that the development of pelvic girdle pain is associated with high levels of ovarian and placental hormones during pregnancy, the evidence is inconsistent (MacLennan et al., 1986; Albert et al., 1997; Kristiansson et al., 1999). Age at menarche displays an inverse association with pelvic girdle pain (Bjelland et al., 2011), and age at menarche may be an indicator of a woman's endogenous hormonal levels (Apter et al., 1989). Therefore, a link between pre-pregnancy and intra-pregnancy hormonal factors regarding the development of pelvic girdle pain is plausible.
Given this perspective, it is also conceivable that exogenous hormonal exposure plays a role. In fact, it has been suggested that hormonal contraceptive use is associated with an increased risk of pelvic girdle pain during pregnancy (Bjorklund et al., 2000; Kumle et al., 2004; Mogren and Pohjanen, 2005; Albert et al., 2006). Although the mechanisms are unclear, hormonal contraceptives reportedly influence collagen synthesis in connective tissue (Hansen et al., 2009) and alter bone metabolism (Lopez et al., 2011). Such changes may interact with the normal bone and joint changes that occur in the pelvis during pregnancy (Wurdinger et al., 2002) and increase the woman's susceptibility to pain. In contrast, hormonal contraceptive use has been associated with positive effects regarding gynaecological pelvic pain in non-pregnant women (Maguire and Westhoff, 2011).
During the past five decades, hormonal contraception has been used by millions of women worldwide. Still, evidence about the association between oral contraceptives and pelvic girdle pain during pregnancy remains inconclusive (Bjorklund et al., 2000; Kumle et al., 2004; Mogren and Pohjanen, 2005; Albert et al., 2006) and may lead to uncertainty for some women regarding contraceptive counseling. Moreover, the possible influence of progestin injections and progestin intrauterine devices on the development of pelvic girdle pain has not been evaluated. Our aim was to study the association between pre-pregnancy hormonal contraceptive use and the presence of pelvic girdle pain in more than 90 000 pregnancies, at 30 weeks of pregnancy.
Materials and Methods
Study design, study population and follow-up
In 1999–2008, all pregnant women scheduled to give birth at 50 hospitals in Norway were targeted for recruitment into the Norwegian Mother and Child Cohort Study (www.fhi.no/morogbarn), conducted by the Norwegian Institute of Public Health (Magnus et al., 2006). The women were recruited in connection with the routine ultrasound examination at pregnancy weeks 17–18. This examination is part of the public antenatal care program and is offered to all pregnant women. The study had no exclusion criteria, and 38.5% of all eligible women who gave birth in Norway agreed to participate. Each woman was able to participate with more than one pregnancy. The Norwegian Mother and Child Cohort Study is described in detail elsewhere (Magnus et al., 2006).
Data were obtained through two self-administered questionnaires that were sent and returned by mail. Of women who agreed to participate, 94.7% returned the first questionnaire. This questionnaire was completed during the second trimester [mean 17.4 weeks, standard deviation (SD) 2.6 weeks] and included questions about sociodemographic factors, general health, reproductive history and hormonal contraceptive use. The second questionnaire, which was completed during the third trimester (mean 30.6 weeks, SD 2.0 weeks) comprised questions about maternal health status during pregnancy, including pelvic girdle pain. The response rate of the second questionnaire was 91.6%, and we included 93 054 pregnancies in women who had completed both questionnaires. We excluded 1333 pregnancies in which more than one hormonal contraceptive method during the final year before pregnancy was reported, leaving a total of 91 721 pregnancies in our study sample.
Study factors
The location of pelvic girdle pain was classified on the basis of answers to the following questions: ‘Do you have pain in the pelvic girdle?’ and ‘If you have pain in the pelvic girdle, where is the pain located?’ One or more locations could be specified: the frontal part of the pelvis, one side of the rear part of the pelvis and both sides of the rear part of the pelvis. Pelvic girdle pain was defined as combined anterior pelvic pain and bilateral posterior pelvic pain (Albert et al., 2006).
Hormonal contraceptive use during the final year before pregnancy was reported on the basis of the following question: ‘Have you at any time during the last year used the following methods to prevent becoming pregnant?’ One or more options could be specified: the response categories included combined oral contraceptive pills (combined estrogen/progestin), progestin-only contraceptive pills, progestin injections (depot medroxyprogesterone acetate) and progestin intrauterine device (levonorgestrel). In the analyses, hormonal contraceptive use was coded as: (i) no hormonal contraceptives during the last year (reference); (ii) combined oral contraceptive pills; (iii) progestin-only contraceptive pills; (iv) progestin injections and (v) progestin intrauterine devices. The data also included information about other contraceptive methods, such as copper intrauterine devices.
We also had information about oral contraceptive use during the final 4 months before pregnancy and at the time of being pregnant. Women who reported the use of oral contraceptives at one time point but not at the next were defined as having stopped using oral contraceptives. Oral contraceptive use during the final 4 months before pregnancy and at the time of being pregnant were coded as (i) no oral contraceptives the last year (reference); (ii) combined oral contraceptive pills; (iii) progestin-only contraceptive pills and (iv) cessation of oral contraceptives. Lifetime duration of oral contraceptive use was reported on the basis of the following question: ‘If you have used combined oral contraceptive pills and/or progestin-only contraceptive pills, for how long altogether did you use them?’ The response categories were <1, 1–3, 4–6, 7–9 and ≥10 years.
In the multivariate statistical models, we included the number of previous deliveries, maternal age, educational level, body mass index (BMI), age at menarche, other pain conditions and symptoms of premenstrual tension as possible confounders of the association between hormonal contraceptive use and pelvic girdle pain. The number of previous deliveries was coded as no delivery and ≥1 deliveries. Educational level was coded as ≤12, 13–16, ≥17 years and missing. BMI during Week 17 of pregnancy was calculated as weight/height² (kilograms per square meter). Information about other pain conditions (coded as present or not) included low back pain before the first pregnancy, rheumatic diseases, fibromyalgia, migraine and endometriosis. Premenstrual depressive symptoms were reported on the basis of the following questions: ‘Are you usually depressed or irritable before your period?’ and ‘If yes, does this feeling disappear after you get your period?’ and coded as: (i) no symptoms; (ii) mild symptoms; (iii) moderate symptoms; (iv) severe symptoms; (v) symptoms not alleviated in the menstrual period; and (vi) missing.
Statistical methods
Hormonal contraceptive use is presented as proportions (%). Group differences were examined by χ2 tests and logistic regression analyses. The associations of pre-pregnancy hormonal contraceptive use and duration of oral contraceptive use with the presence of pelvic girdle pain were estimated as crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) using logistic regression analyses. We used generalized estimating equations with the logit link function and exchangeable correlations to correct for possible correlations between pregnancies (>1 pregnancy per study participant). We studied the associations in all women, and we performed separate analyses in strata according to parity (no delivery and ≥1 deliveries), maternal age (<25 and ≥25 years) and BMI (<25 and ≥25 kg/m2). A 5% significance level was chosen for the analyses. The statistical software package SPSS version 20.0 was used for the statistical analyses (SPSS Inc, Chicago, IL, USA).
Ethical considerations
The Norwegian Mother and Child Cohort Study was approved by all of the Regional Committees for Medical Research Ethics and by the Norwegian Data Inspectorate. All participants signed an informed consent form.
Results
Upon inclusion at pregnancy week 17, the mean maternal age was 29.8 years (SD 4.6 years). Four out of five women had a planned pregnancy and 47.5% were first-time mothers. During the third trimester, 14.8% of all women reported pelvic girdle pain. During the final year before the present pregnancy, 32.4 and 5.4%, respectively, had used combined oral contraceptive pills or progestin-only contraceptive pills (Table I). Among women who reported the use of oral contraception, 47.0% (16 318/34 704) reported cessation 4 months before pregnancy. At the time of being pregnant, the corresponding proportion was 95.6% (32 954/34 704). During the final year before pregnancy, 4.7 and 0.5%, respectively, had used progestin intrauterine devices or progestin injections.
Table I.
Baseline characteristics of the study sample (n = 91 721).
| Characteristics | Number (%) | Mean (SD) |
|---|---|---|
| Parity | ||
| Primiparous | 43 593 (47.5) | |
| Multiparous | 48 128 (52.5) | |
| Maternal age (years) | 29.8 (4.6) | |
| BMI (kg/m2)a | 25.1 (4.2) | |
| Age at menarche (years)b | 13.0 (1.4) | |
| Planned pregnancy | ||
| Yes | 73 627 (80.3) | |
| No | 17 070 (18.6) | |
| Missing | 1024 (1.1) | |
| Hormonal contraceptive use last year before pregnancy | ||
| None | 52 310 (57.0) | |
| Combined oral contraceptive pills | 29 732 (32.4) | |
| Progestin-only contraceptive pills | 4972 (5.4) | |
| Progestin injections | 414 (0.5) | |
| Progestin intrauterine devices | 4293 (4.7) | |
| Oral contraceptive use last 4 months before pregnancyc | ||
| No hormonal contraceptives last year | 52 310 (60.1) | |
| Combined oral contraceptive pills | 15 810 (18.2) | |
| Progestin-only contraceptive pills | 2576 (3.0) | |
| Cessation of oral contraceptives | 16 318 (18.8) | |
| Oral contraceptive use at the time of being pregnantc | ||
| No hormonal contraceptives last year | 52 310 (60.1) | |
| Combined oral contraceptive pills | 1372 (1.6) | |
| Progestin-only contraceptive pills | 378 (0.4) | |
| Cessation of oral contraceptives | 32 954 (37.9) | |
BMI, body mass index; SD, standard deviation.
an = 87 216.
bn = 90 535.
cn = 87 014.
Combined oral contraceptive pills
Pelvic girdle pain was present in 12.9% of women who had used combined oral contraceptive pills during the last pre-pregnancy year, compared with 15.3% of women who did not use hormonal contraceptives [crude odds ratio (OR) 0.82; 95% confidence interval (CI): 0.79–0.86) (Table II). After adjustment for the other study factors, no association was observed between combined oral contraceptive pills and pelvic girdle pain. The number of previous deliveries was the main confounder of the association between hormonal contraceptive use and pelvic girdle pain. When participants were analysed in groups stratified by parity, the use of combined oral contraceptive pills the final year before pregnancy was inversely associated with pelvic girdle pain in primiparous women (adjusted OR 0.87; 95% CI: 0.81–0.93) (Table II). Conversely, the use of combined oral contraceptive pills was associated with a marginally increased prevalence of pelvic girdle pain in multiparous women (adjusted OR 1.08; 95% CI: 1.01–1.15). No associations between combined oral contraceptive pills and pelvic girdle pain were observed when participants were stratified by maternal age or BMI (data not shown). Furthermore, there was no association between pelvic girdle pain and combined oral contraceptive pills at 4 months before pregnancy or at the time of being pregnant (Table III). Finally, lifetime duration of combined oral contraceptive use was not associated with pelvic girdle pain (Table IV).
Table II.
Crude and adjusted ORs with 95% CIs for the impact of hormonal contraceptive use in the last year before pregnancy on pelvic girdle pain in 91 721 Norwegian pregnancies (1999–2008).
| Hormonal contraceptive use | No. persons | Pelvic girdle pain |
||
|---|---|---|---|---|
| No. cases (%) | Crude OR (95% CI) | Adjusted OR (95% CI) | ||
| All women (n = 91 721)a | ||||
| None | 52 310 | 7995 (15.3) | Ref. | Ref. |
| Combined oral contraceptive pills | 29 732 | 3845 (12.9) | 0.82 (0.79–0.86)*** | 0.97 (0.92–1.01) |
| Progestin-only contraceptive pills | 4972 | 815 (16.4) | 1.09 (1.00–1.18)* | 0.97 (0.89–1.05) |
| Progestin injections | 414 | 69 (16.7) | 1.11 (0.85–1.44) | 0.98 (0.75–1.30) |
| Progestin intrauterine devices | 4293 | 890 (20.7) | 1.45 (1.34–1.57)*** | 1.20 (1.11–1.31)*** |
| Primiparous women (n= 43 593)b | ||||
| None | 20 900 | 2413 (11.0) | Ref. | Ref. |
| Combined oral contraceptive pills | 20 586 | 2009 (9.8) | 0.87 (0.82–0.93)*** | 0.87 (0.81–0.93)*** |
| Progestin-only contraceptive pills | 704 | 87 (12.4) | 1.14 (0.91–1.43) | 1.15 (0.91–1.46) |
| Progestin injections | 157 | 24 (15.3) | 1.46 (0.94–2.26) | 1.25 (0.80–1.97) |
| Progestin intrauterine devices | 246 | 33 (13.4) | 1.25 (0.87–1.81) | 1.25 (0.85–1.85) |
| Multiparous women (n = 48 128)c | ||||
| None | 30 410 | 5582 (18.4) | Ref. | Ref. |
| Combined oral contraceptive pills | 9146 | 1836 (20.1) | 1.12 (1.05–1.19)*** | 1.08 (1.01–1.15)** |
| Progestin-only contraceptive pills | 4268 | 728 (17.1) | 0.92 (0.84–1.00)* | 0.96 (0.88–1.05) |
| Progestin injections | 257 | 45 (17.5) | 0.94 (0.68–1.30) | 0.87 (0.62–1.23) |
| Progestin intrauterine devices | 4047 | 857 (21.2) | 1.20 (1.10–1.31)*** | 1.22 (1.12–1.33)*** |
CI, confidence interval; OR, odds ratio.
aAdjusted for parity, maternal age, educational level, BMI, age at menarche, other pain conditions and premenstrual depressive symptoms (n = 86 139).
bAdjusted for maternal age, educational level, BMI, age at menarche, other pain conditions and premenstrual depressive symptoms (n = 40 768).
cAdjusted for maternal age, educational level, BMI, age at menarche, other pain conditions and premenstrual depressive symptoms (n = 45 371).
*Statistically significant at 0.05 level.
**Statistically significant at 0.01 level.
***Statistically significant at 0.001 level.
Table III.
Crude and adjusted ORs with 95% CIs for the impact of oral contraceptive use 4 months before pregnancy and at the time of being pregnant on pelvic girdle pain in 87 014 Norwegian pregnancies (1999–2008).
| Oral contraceptive use | No. persons | Pelvic girdle pain |
||
|---|---|---|---|---|
| No. cases (%) | Crude OR (95% CI) | Adjusted ORa (95% CI) | ||
| 4 months before pregnancy | ||||
| No hormonal contraceptives last year | 52 310 | 7995 (15.3) | Ref. | Ref. |
| Combined oral contraceptive pills | 15 810 | 2110 (13.3) | 0.85 (0.81–0.90)** | 1.00 (0.94–1.05) |
| Progestin-only contraceptive pills | 2576 | 429 (16.7) | 1.11 (1.00–1.23) | 1.00 (0.90–1.12) |
| Cessation of oral contraceptives | 16 318 | 2121 (13.0) | 0.83 (0.79–0.87)** | 0.94 (0.89–0.99)* |
| At the time of being pregnant | ||||
| No hormonal contraceptives last year | 52 310 | 7995 (15.3) | Ref. | Ref. |
| Combined oral contraceptive pills | 1372 | 232 (16.9) | 1.13 (0.98–1.30) | 1.16 (0.99–1.35) |
| Progestin-only contraceptive pills | 378 | 69 (18.3) | 1.24 (0.95–1.61) | 1.00 (0.76–1.32) |
| Cessation of oral contraceptives | 32 954 | 4359 (13.2) | 0.85 (0.81–0.88)** | 0.96 (0.92–1.00) |
CI, confidence interval; OR, odds ratio.
aAdjusted for maternal age, educational level, BMI, age at menarche, other pain conditions and premenstrual depressive symptoms (n = 81 703).
*Statistically significant at 0.05 level.
**Statistically significant at 0.001 level.
Table IV.
Crude and adjusted ORs with 95% CIs for the impact of lifetime duration of oral contraceptives on pelvic girdle pain in 91 721 Norwegian pregnancies (1999–2008).
| Variables | No. persons | Pelvic girdle pain |
||
|---|---|---|---|---|
| No. cases (%) | Crude OR (95% CI) | Adjusted ORa (95% CI) | ||
| Combined oral contraceptive pills | ||||
| Never user | 22 437 | 3657 (16.3) | Ref. | Ref. |
| <1 year | 6043 | 1010 (16.7) | 1.03 (0.95–1.11) | 1.03 (0.95–1.12) |
| 1–3 years | 15 758 | 2436 (15.5) | 0.94 (0.89–0.99)* | 0.99 (0.93–1.05) |
| 4–6 years | 18 333 | 2658 (14.5) | 0.87 (0.82–0.92)** | 1.00 (0.94–1.06) |
| 7–9 years | 15 981 | 2067 (12.9) | 0.76 (0.72–0.81)** | 0.94 (0.88–1.00)* |
| ≥10 years | 13 169 | 1786 (13.6) | 0.81 (0.76–0.86)** | 1.04 (0.97–1.11) |
| Progestin-only contraceptive pills | ||||
| Never user | 80 788 | 11 713 (14.5) | Ref. | Ref. |
| <1 year | 6448 | 1184 (18,4) | 1.33 (1.24–1.42)** | 1.05 (0.97–1.12) |
| 1–3 years | 3469 | 552 (15.9) | 1.12 (1.02–1.23)* | 0.97 (0.88–1.07) |
| 4–6 years | 564 | 86 (15.2) | 1.06 (0.84–1.34) | 1.06 (0.84–1.35) |
| 7–9 years | 256 | 43 (16.8) | 1.19 (0.86–1.65) | 1.14 (0.81–1.62) |
| ≥10 years | 196 | 36 (18.4) | 1.33 (0.92–1.92) | 1.49 (1.01–2.20)* |
CI, confidence interval; OR, odds ratio.
aAdjusted for maternal age, parity, educational level, BMI, age at menarche, other pain conditions and premenstrual depressive symptoms (n= 86 139).
*Statistically significant at 0.05 level.
**Statistically significant at 0.001 level.
Progestin-only contraceptive pills
Pelvic girdle pain was reported by 16.4% of women who had used progestin-only contraceptive pills during the last pre-pregnancy year compared with 15.3% in the reference group (crude OR 1.09; 95% CI: 1.00–1.18) (Table II). The significant association disappeared after adjustment for the other study factors, and there was no association between progestin-only contraceptive pills and pelvic girdle pain at 4 months before pregnancy or at the time of being pregnant (Table III). However, the prevalence of pelvic girdle pain increased with respect to lifetime duration of progestin-only contraceptive pills (Table IV).
Progestin intrauterine devices and progestin injections
Pelvic girdle pain was present in 20.7% of women who had used a progestin intrauterine device during the last pre-pregnancy year compared with 15.3% in the reference group. The association remained after adjustment for the other study factors (adjusted OR 1.20; 95% CI: 1.11–1.31) (Table II). The use of a progestin intrauterine device was associated with an increased prevalence of pelvic girdle pain in primiparous and multiparous women, although not significantly in primiparous women, where fewer subjects were available. In comparison, we observed no increased risk of pelvic girdle pain in women who used copper intrauterine devices (data not shown). Progestin injections were not associated with pelvic girdle pain.
Discussion
In this study of 91 721 pregnancies, the use of combined oral contraceptives pre-pregnancy was not associated with pelvic girdle pain up to pregnancy week 30. However, our results suggest a slightly protective effect of combined oral contraceptives in primiparous women that was offset by a marginally increased risk of pelvic girdle pain in multiparous. Furthermore, lifetime duration of exposure to progestin-only contraceptive pills was associated with pelvic girdle pain in a progressive manner. We also observed an increased risk of pelvic girdle pain in women who reported the use of a progestin intrauterine device during the final year before pregnancy.
The participation rate in the Norwegian Mother and Child Cohort Study was 38.5%. Low participation rates are a common problem in epidemiological studies, and may lead to a skewed selection of participants (Nilsen et al., 2009). Compared with the general population of women giving birth in Norway, first-time mothers and women with high educational levels were over-represented, while younger women were under-represented. A recent study on the potential biases of skewed selection in the Norwegian Mother and Child Cohort Study found the prevalence estimates but not the exposure–outcome associations to be influenced by the selection (Nilsen et al., 2009). Hence, it is unlikely that the directions of the estimated associations between hormonal contraceptives and pelvic girdle pain are biased.
Both the outcome measure of pelvic girdle pain and the exposure variables were based on self-reports. We defined pelvic girdle pain as pain located in the anterior pelvis and on both sides in the posterior pelvis. Previously, this designation of pelvic girdle pain has been associated with greater functional disability and more frequent sick leave; it also has a worse prognosis than pain in one or two pelvic locations (Robinson et al., 2006; Bjelland et al., 2013). Therefore, our outcome measure has a high specificity for pain in the pelvic girdle. Because of the broad scope of the Norwegian Mother and Child Cohort Study (Magnus et al., 2006), it is implausible that self-reports of hormonal contraceptives and pelvic girdle pain have caused differential misclassification. However, errors due to self-reporting may have deflated the estimated associations (Grimes and Schulz, 2002). We had no data about the doses of estrogen and progestin used, thus we could not perform dose-specific analysis. Nevertheless, the women were included during 1999–2008, indicating that the majority had used relatively low-dose contraceptive pills.
The large sample size allowed extensive adjustment for potentially confounding factors. The multivariate analyses were adjusted for other pain conditions, including endometriosis. Unfortunately, we had no data regarding dysmenorrhea, which is associated with hormonal contraceptive use (Maguire and Westhoff, 2011) and may also be associated with pelvic girdle pain. Dysmenorrhea has been associated with premenstrual symptoms (Fujiwara and Nakata, 2007), and hormonal contraceptives are frequently prescribed to women with such symptoms (Maguire and Westhoff, 2011); therefore, we adjusted for premenstrual depressive symptoms in the multivariate analyses. However, residual confounding may still remain.
Our findings are consistent with the results of previous studies that report no association between oral contraceptive pills and pelvic girdle pain during pregnancy (Bjorklund et al., 2000; Mogren and Pohjanen, 2005; Albert et al., 2006). However, among 2078 of the women in the Norwegian Women and Cancer Study, there was a positive association between the pre-pregnancy use of combined oral contraceptives and pelvic girdle pain in primiparous women, but not in multiparous women (Kumle et al., 2004). Conversely, our results suggest a negative direction of the association in primiparous women. Because hormonal contraceptive use before and between all previous pregnancies, as well as pelvic girdle pain during all pregnancies, were retrospectively reported at the age of 35–49 years, recall may have influenced their estimated associations. The authors also observed an effect of duration of hormonal contraceptives (not specified) on pelvic girdle pain, supporting our estimated association between the duration of progestin-only contraceptive pills and pelvic girdle pain. Previously, high progesterone levels during pregnancy have been associated with pelvic girdle pain (Kristiansson et al., 1999).
A novel finding in our study is the association between progestin intrauterine devices and pelvic girdle pain. Even though progestin intrauterine devices are often prescribed for women with dysmenorrhea and endometriosis (Maguire and Westhoff, 2011), back pain and pelvic pain are listed as side effects. Furthermore, previous clinical observations have suggested a link with pregnancy-related pelvic girdle pain (Sverdrup and Kristiansson, 2004; Fotoohi and Melin, 2010).
In addition to effective birth control and multiple health benefits (Blumenthal and Edelman, 2008; Maguire and Westhoff, 2011), hormonal contraceptives have been associated with cardiovascular and musculoskeletal adverse effects (Lidegaard et al., 2011; Lopez et al., 2011). Recently, researchers have reported that combined oral contraceptives may impair insulin sensitivity and induce an increase in markers of chronic inflammation (Piltonen et al., 2012). Estrogen and progesterone receptors have been identified in the pubic symphysis of rodents, suggesting that these hormones are involved in the remodeling of the pelvic joints during pregnancy (Wang et al., 2009). Combined oral contraceptives appear to inhibit collagen synthesis in connective tissue, and it has been speculated that this finding is related to the low bioavailability of insulin-like growth factor I in users of combined oral contraceptives (Hansen et al., 2009). Moreover, the altered expression of estrogen receptors and release of tumor necrosis factor α have been demonstrated in macrophages isolated from users of combined oral contraceptives (Campesi et al., 2012).
We observed no positive association between oral contraceptive use during the final year before pregnancy and pelvic girdle pain. However, most women stop using hormonal contraceptives at some time before pregnancy. To what extent adverse effects are reversible after discontinuation is not known. If hormonal contraceptives influence the pelvic girdle, it would be expected that women who continue oral contraceptive use until pregnancy are at the greatest risk of developing pain. Oral contraceptive use, whether at 4 months before pregnancy or at the time of being pregnant, was not associated with pelvic girdle pain; this finding suggests there are minimal effects on the pelvic girdle after discontinuation. In contrast, it is conceivable that administration of hormonal contraceptives to women with postpartum pelvic girdle pain might negatively influence the long-term prognosis.
We also observed no association between the duration of use of combined oral contraceptives and pelvic girdle pain. However, exposure to progestin-only contraceptive pills for 10 years or longer and use of a progestin intrauterine device were associated with an increased risk of pelvic girdle pain. Long-term stimulation to unopposed progestin, as a result of progestin injections, has been linked to low ovarian estrogen production and impaired bone mineral density (Nappi et al., 2012). Although the changes are most likely reversible, this finding has resulted in warnings against the long-term use of progestin injections by young women (Blumenthal and Edelman, 2008). We observed no significant association between progestin injections and pelvic girdle pain. However, only 414 (0.5%) women reported progestin injections during the final year before pregnancy, and we had no available information about the duration of progestin injections. Progestin-only contraceptive pills and progestin intrauterine devices result in lower systemic progestin levels than progestin injections, and knowledge about their possible adverse effects is limited (Nappi et al., 2012). Nevertheless, very low estrogen levels, osteoporosis and low back pain have been observed in connection with the progestin intrauterine device (Greiner et al., 2009). Although low-dose progestin-only contraceptives (pills or intrauterine devices) are considered safer than progestin injections, they also may have adverse musculoskeletal effects.
In conclusion, our results confirm no adverse influence of the use of combined oral contraceptives on the development of pelvic girdle pain. This finding has important clinical implications because three out of four women who reported using hormonal contraceptives during the final year before pregnancy had used combined oral contraceptives. However, the results imply adverse effects of progestin intrauterine devices and of long-term exposure to progestin-only contraceptive pills. Further studies should address the musculoskeletal effects of long-term exposure to low-dose progestin-only contraceptives and how hormonal contraception after pregnancy affects the prognosis of pelvic girdle pain.
Authors' roles
E.K.B. and M.E.G. planned the study and performed the analyses. E.K.B. wrote the major part of the paper. E.K.B., P.K., H.N., S.V. and M.E.G. discussed the design, edited the paper and agreed on the final version. E.K.B. and M.E.G. are guarantors. All authors had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analyses.
Funding
The Norwegian Mother and Child Cohort Study is supported by the Norwegian Ministry of Health and the Ministry of Education and Research, NIH/NIEHS (contract no. N01-ES-75558), NIH/NINDS (grant no. 1 UO1 NS 047537-01 and grant no. 2 UO1 NS 047537-06A1) and the Norwegian Research Council/FUGE (grant no. 151918/S10). The present study was supported by the Norwegian Research Council.
Conflict of interest
None declared.
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