Age at menarche and pelvic girdle syndrome in pregnancy: a population study of 74 973 women

Authors


EK Bjelland, MSc, PhD student, Division of Mental Health, Norwegian Institute of Public Health, PO Box 4404 Nydalen, N-0403 Oslo, Norway. Email ElisabethKrefting.Bjelland@fhi.no

Abstract

Please cite this paper as: Bjelland E, Eberhard-Gran M, Nielsen C, Eskild A. Age at menarche and pelvic girdle syndrome in pregnancy: a population study of 74 973 women. BJOG 2011;118:1646–1652.

Objective  To study the association of age at menarche with presence of pelvic girdle syndrome in pregnancy.

Design  Population study.

Setting  Norway 1999–2007.

Population  A total of 74 973 pregnant women in the Norwegian Mother and Child Cohort Study.

Methods  Data were obtained by self-administered questionnaires in weeks 17 and 30 of gestation.

Main outcome measure  Pelvic girdle syndrome in pregnancy at 30 weeks of gestation, defined as pain in the pubic symphysis in the anterior pelvis and in both sacroiliac joints in the posterior pelvis.

Results  The prevalence of pelvic girdle syndrome was 20.6% (328/1593) in women with menarche before the age of 11, it was 16.3% (3200/22 044) in women with menarche at the age of 12 and 12.7% (1252/9859) in women with menarche after the age of 14 (chi-square test for trend, P < 0.001). The inverse association of age at menarche with pelvic girdle syndrome remained after adjustment for body mass index, maternal age, parity, educational level, previous low back pain, emotional distress and physically demanding work. Women with early menarche and high body mass index had the highest prevalence of pelvic girdle syndrome, but the association of early menarche with pelvic girdle syndrome was similar in women with and without high body mass index.

Conclusions  Early menarche was associated with increased prevalence of pelvic girdle syndrome in pregnancy. Factors associated with early menarche may play a role in the development of pelvic girdle pain.

Introduction

Pelvic girdle pain is a common complaint in pregnancy and may cause disability.1,2 In recent studies in Europe, about 30% of all pregnant women report pain in either the sacroiliac joints in the posterior pelvis or in the pubic symphysis in the anterior pelvis.2,3 Some reports suggest that 7% or more of all pregnant women may be severely affected by pelvic girdle pain, leading to difficulty walking.2,4 Despite this, uniform diagnostic criteria are lacking and the aetiology remains unclear.1

Pelvic girdle pain has been explained by biomechanical alterations in the pelvic joints because of hormonal and postural changes during pregnancy,5 but may also be a result of increased pain sensitivity in women who develop such pain. Degenerative joint diseases have been linked to female reproductive hormones,6 and estrogens in combination with relaxin may initiate collagen degradation in synovial joints.7,8 Also, pain sensitivity may be influenced by female reproductive hormones, as women report more pain after puberty than men.9,10

Early menarche has been used as an indicator of high estrogen levels because elevated estrogen levels have been found in women with early menarche11,12 and estrogen-dependent cancers have been associated with early menarche.11,13 Early menarche seems to increase the risk of chronic musculoskeletal pain.14 It is not known whether high estrogen levels are associated with pelvic girdle pain in pregnancy. However, such an association is plausible because high body mass index (BMI) increases the risk of pelvic girdle pain4 and women with high BMI tend to have elevated free estrogen levels.15 These findings suggest that early menarche, as an indicator of high levels of estrogens, may be associated with pelvic girdle pain in pregnancy.

Two previous studies have assessed the relationship between age at menarche and pelvic girdle pain during pregnancy, but no significant association was found.16,17 These studies, however, had limited statistical power.

Our aim was to study the association of age at menarche and pelvic girdle syndrome (pain in the anterior pelvis and in the posterior pelvis bilaterally) in pregnancy.

Methods

Study design, recruitment and study population

During the years 1999–2009, as part of the Norwegian Institute of Public Health ‘Norwegian Mother and Child Cohort Study’, efforts were made to collect data on all pregnant women scheduled to give birth in Norway.18 There are a total of 52 hospitals with a maternity ward in Norway, and all but two recruited women to the study. The women were recruited at the routine fetal ultrasound examination in weeks 17–18 of gestation. This examination is part of the public antenatal care programme and is offered to all pregnant women. There were no exclusion criteria, the participation rate was 41% and 95% of the participants completed the two questionnaires used in our data analysis. We excluded 996 women who had not answered the question on age at menarche, leaving a total of 74 973 women in our study.

Data collection and follow up

Data were obtained by two self-administered questionnaires, sent and returned by mail. The first questionnaire was completed in the second trimester (mean 17.4 weeks of gestation, standard deviation [SD] 2.8 weeks) and included questions about socio-demographic factors, general health, and obstetrical and gynaecological history. The second questionnaire, which included questions on health during pregnancy, was completed in the early part of the third trimester (mean 30.6 weeks of gestation, SD 2.0 weeks).18

Study factors

Pelvic girdle syndrome (PGS) was defined on the basis of the following questions in week 30 of gestation. Do you have pain in the pelvis (yes/no)? If you have pain in the pelvis, where is the pain located: in the frontal part of the pelvis, on one side of the rear part of the pelvis, or on both sides of the rear part of the pelvis? We defined PGS as present if the women reported pain in the anterior pelvis and on both sides in the posterior pelvis.3

Age at menarche was reported on the basis of the following question: at what age (years old) did you have your first menstruation? Age at menarche was coded: <11, 11, 12, 13, 14 and >14 years (reference). This report is based on secondary analysis of a previous study,4 in which we identified high BMI, young maternal age, parity, low educational level, previous low back pain, emotional distress, and physically demanding work as risk factors of PGS. These variables were all included in our analyses as potentially confounding factors. The BMI in the second trimester was calculated as weight (kg)/height squared (m²) and coded: <25, 25–29, 30–34, ≥35 and missing. Maternal age was coded <25, 25–34 and ≥35 years old, parity was coded first-time mother and para ≥ 1, and educational level was coded <12, 12, 13–16, ≥17 years of education and missing. Presence of low back pain before the first pregnancy was coded yes and no. Emotional distress was measured in the second trimester using the Symptom Checklist-5 (SCL-5), a short-form of the Hopkins Symptom Checklist-25.19 The SCL-5 consists of five questions on symptoms of anxiety and depression. We defined a mean SCL-5 score ≥ 2.0 as indicating the presence of emotional distress. Physically demanding work at inclusion was coded on the basis of the response to the statement: I perform physically demanding work: yes (agree/agree mostly), no (do not agree very much/do not at all agree) and missing.

Statistical methods

The proportion (%) of women with PGS according to year of menarche was calculated. Differences in mean values between groups were tested with one-way analysis of variance. The trend in the estimated proportions and mean values across age at menarche was assessed by chi-square tests for trend and linear regression analysis, respectively. The association of age at menarche with PGS was estimated as crude and adjusted odds ratios with 95% confidence intervals (95% CI) using logistic regression analyses. We studied the association in all 74 973 women, and we also made separate analyses in women with BMI < 25 and in women with BMI ≥ 25. Possible interactions were tested by inclusion of interaction joints in the multivariable analyses. The statistical package SPSS version 17.0 was used for the statistical analyses (SPSS Inc., Chicago, IL, USA).

Results

The mean maternal age in our study sample was 29.7 years (SD 4.6 years) (Table 1). Forty-six percent of the women were first-time mothers. The mean age at menarche was 13.0 years (SD 1.4 years) and the mean BMI was 25.1 (SD 4.2) in the second trimester.

Table 1.   Characteristics of 74 973 pregnant women in Norway (1999–2007)
CharacteristicsNumber (%)Mean (SD)
  1. BMI, body mass index; SD, standard deviation.

  2. *n = 71 328.

Parity  
First-time mothers34 676 (46.3) 
Para ≥ 142 297 (53.7) 
Maternal age (years) 29.7 (4.6)
BMI (kg/m²)* 25.1 (4.2)
Age at menarche (years) 13.0 (1.4)
<111593 (2.1) 
117125 (9.5) 
1218 724 (25.0) 
1322 044 (29.4) 
1415 628 (20.8) 
>149859 (13.2) 
Interval since menarche (years) 16.7 (4.7)

In the early third trimester, 15.1% of all women (11 295/74 973) reported PGS. The proportion of women with PGS decreased with increasing age at menarche (Figure 1). Of women with menarche before the age of 11, 20.6% had PGS, compared with 14.5% of women with menarche at the age of 13, and 12.7% of women with menarche after the age of 14 (chi-square test for trend, P < 0.001) (Table 2). The crude odds ratio of PGS was 1.8 (95% CI 1.6–2.0) comparing menarche before the age of 11 with menarche after the age of 14. After adjustment for BMI, the corresponding odds ratio was attenuated to 1.5 (95% CI 1.3–1.7), and the decrease in odds ratio by increasing age at menarche remained. Adjustment for other study factors did not further attenuate the association of age at menarche with PGS (Table 2). In addition to early menarche, high BMI, low maternal age, previous delivery, low educational level, previous low back pain, emotional distress, and physically demanding work were associated with increased prevalence of PGS.

Figure 1.

 Proportion (%) of women who reported pelvic girdle syndrome at 30 weeks of gestation according to age at menarche.

Table 2.   The association of age at menarche with pelvic girdle syndrome, estimated as crude and adjusted odds ratio (OR) with 95% CI (n = 74 973)
VariablesNo. personsPelvic girdle syndrome
No. cases (%)Crude OR (95% CI)Adjusted OR**** (95% CI)Adjusted OR***** (95% CI)
  1. BMI, body mass index; CI, confidence interval; OR, odds ratio.

  2. ****Adjusted for BMI.

  3. *****Adjusted for BMI, maternal age, parity, educational level, previous low back pain, physically demanding work and emotional distress.

  4. *< 0.05; **P < 0.01; ***P < 0.001.

Age at menarche (years)
<111593328 (20.6)1.8 (1.6–2.0)***1.5 (1.3–1.7)***1.4 (1.2–1.6)***
1171251307 (18.3)1.5 (1.4–1.7)***1.3 (1.2–1.5)***1.3 (1.2–1.4)***
1218 7243045 (16.3)1.3 (1.2–1.4)***1.2 (1.1–1.3)***1.2 (1.1–1.3)***
1322 0443200 (14.5)1.2 (1.1–1.3)***1.1 (1.0–1.2)**1.1 (1.0–1.2)*
1415 6282163 (13.8)1.1 (1.0–1.2)**1.1 (1.0–1.2)*1.1 (1.0–1.2)
>1498591252 (12.7)1.01.01.0
BMI (kg/m2)
<25.041 0945173 (12.3)1.01.01.0
25.0–29.921 5273744 (17.4)1.5 (1.4–1.6)***1.5 (1.4–1.5)***1.4 (1.3–1.4)***
30–34.965471403 (21.4)1.9 (1.8–2.1)***1.9 (1.7–2.0)***1.6 (1.5–1.8)***
≥35.02160542 (25.1)2.4 (2.1–2.6)***2.2 (2.0–2.5)***1.9 (1.7–2.1)***
Missing3645533 (14.6)1.2 (1.1–1.3)***1.2 (1.1–1.3)***1.2 (1.1–1.3)**
Maternal age
<2596201522 (16.1)1.1 (1.0–1.2)** 1.4 (1.3–1.5)***
25–3454 4768178 (15.0)1.1 (1.0–1.1) 1.2 (1.1–1.3)***
≥3510 8771565 (14.4)1.0 1.0
Parity
Para 034 6763640 (10.5)1.0 1.0
Para ≥ 142 2977655 (19.0)2.0 (1.9–2.1)*** 2.2 (2.1–2.3)***
Educational level (years)
<1257431147 (20.0)2.0 (1.8–2.1)*** 1.3 (1.2–1.5)***
1220 5053598 (17.5)1.7 (1.6–1.8)*** 1.2 (1.2–1.3)***
13–1629 4864276 (14.5)1.3 (1.3–1.4)** 1.1 (1.1–1.2)***
≥1715 3891737 (11.3)1.0 1.0
Missing3850573 (13.9)1.3 (1.1–1.4)*** 1.2 (1.0–1.3)**
Low back pain
No60 5408319 (13.7)1.0 1.0
Yes14 4332976 (20.6)1.6 (1.6–1.7)*** 1.6 (1.6–1.7)***
Physically demanding work
No46 3635935 (12.8)1.0 1.0
Yes21 6774167 (19.2)1.6 (1.6–1.7)*** 1.4 (1.4–1.5)***
Missing69331193 (17.2)1.4 (1.3–1.5)*** 1.1 (1.1–1.2)**
Emotional distress
No < 2.0068 9029994 (14.5)1.0 1.0
Yes ≥ 2.0048791143 (23.4)1.8 (1.7–1.9)*** 1.6 (1.5–1.8)***
Missing1192158 (13.2)0.9 (0.8–1.1) 0.9 (0.7–1.0)

The BMI was associated with both age at menarche and PGS. Women with early menarche had higher BMI in the second trimester than women with late menarche, and per year delay in menarche, the mean BMI decreased by 0.7 kg/m2 (95% CI 0.5–0.8 kg/m2) (test for linear trend, P < 0.001). Hence, women with both early menarche and high BMI had the highest prevalence of PGS (Figure 2). PGS was reported by 27.8% (141/508) of the women with menarche before the age of 12 and BMI ≥ 35, and by 11.1% (1808/16 270) of women with menarche after the age of 13 and BMI < 25. The association of age at menarche with PGS displayed the same pattern both in women with BMI < 25 and in women with BMI ≥ 25 (Table 3), and no interaction between BMI and age at menarche regarding the risk of PGS could be estimated (Pinteraction = 0.385). The inverse association of age at menarche with PGS was present in first-time mothers as well as in mothers with one or more previous deliveries (chi-square test for trend, < 0.001 in both groups, data not shown).

Figure 2.

 Prevalence of pelvic girdle syndrome according to age at menarche and body mass index (kg/m2).

Table 3.   The association of age at menarche with pelvic girdle syndrome, estimated as crude and adjusted odds ratio (OR) with 95% CI in women with body mass index (BMI) < 25 (n = 41 094) and in women with BMI ≥ 25 (n = 30 234)
VariablesNo. personsPelvic girdle syndrome
No. cases (%)Crude OR (95% CI)Adjusted OR**** (95% CI)
  1. BMI, body mass index; CI, confidence interval; OR, odds ratio.

  2. ****Adjusted for maternal age, parity, educational level, previous low back pain, physically demanding work and emotional distress.

  3. *< 0.05; **P < 0.01; ***P < 0.001.

BMI <25
Age at menarche (years)
 <1153981 (15.0)1.5 (1.2–1.9)**1.4 (1.1–1.9)**
 113018442 (14.6)1.5 (1.3–1.6)***1.4 (1.2–1.6)***
 1289611198 (13.4)1.3 (1.2–1.4)***1.3 (1.2–1.4)***
 1312 3061544 (12.5)1.2 (1.1–1.3)***1.2 (1.1–1.3)***
 1496871112 (11.5)1.1 (1.0–1.2)1.1 (1.0–1.2)
 >146583696 (10.6)1.01.0
BMI ≥ 25
Age at menarche (years)
 <11979225 (23.0)1.4 (1.2–1.7)***1.3 (1.1–1.6)**
 113764811 (21.5)1.3 (1.1–1.5)***1.3 (1.1–1.4)***
 1288661712 (19.3)1.1 (1.0–1.3)*1.1 (1.0–1.2)
 1386971522 (17.5)1.0 (0.9–1.1)1.0 (0.9–1.1)
 145163936 (18.1)1.0 (0.9–1.2)1.0 (0.9–1.2)
 >142765483 (17.5)1.01.0

Discussion

In this study of 74 973 women, the prevalence of pelvic girdle syndrome (PGS) in pregnancy was inversely associated with age at menarche. PGS was reported by 20.6% of the women with menarche before the age of 11 and by 12.7% with menarche after the age of 14. Women with early menarche and high BMI had the highest prevalence of PGS, but the association of early menarche with PGS was similar in women with and without high BMI.

Compared with the general pregnant population in Norway, first-time mothers and women with high socio-economic status were over-represented in our study sample, whereas young mothers were under-represented.18 The overall prevalence of PGS in our study may therefore represent an underestimate because women who become mothers at an early age may also have had early menarche. It is, however, unlikely that the direction of the association of age at menarche with PGS is biased.20

The location and intensity of pelvic girdle pain were based on self-reports and not on clinical examination. There is no standard of clinical signs and symptoms that results in a diagnosis of PGS. To ensure that our outcome measure included true pelvic girdle pain, reported pain in the anterior pelvis in addition to pain on both sides in the posterior pelvis was used as the outcome measure. Such classification of pelvic girdle pain has been associated with greater functional disability, more frequent sick leave and worse prognosis than pain in one or two pelvic locations.2,3

Age at menarche is a significant event in a woman’s reproductive life. Previous studies have found recalled and actual age at menarche to be moderately to highly correlated.21–23 A long time interval from menarche to data collection may result in erroneous reporting of age at menarche. In our study, women with early menarche had longer time interval between menarche and the index pregnancy than women with late menarche (data not shown). There is, however, little reason to believe that women who reported early menarche should systematically report more PGS.

The association of age at menarche with PGS remained statistically significant after adjustment for BMI, maternal age, parity, low educational level, previous low back pain, emotional distress and physically demanding work. These factors have previously been associated with PGS.4 Nevertheless, confounding may still remain. Our main finding is, however, supported both in women with and without high BMI.

Studies on the association of age at menarche with pregnancy-related pelvic girdle pain are scarce.16,17,24 A cross-sectional study of 891 women found no difference in age at menarche in pregnant women with and without low back pain or pelvic girdle pain.17 The outcome measure in that study included both low back pain and pelvic girdle pain, and 72% of the women reported such pain. Having both low back pain and pelvic girdle pain as the outcome may have lowered the specificity for pelvic girdle pain and subsequently, the association between age at menarche and pelvic girdle pain may have been underestimated. Similarly, a retrospective study of 1861 first-time mothers found no association between age at menarche and pelvic girdle pain in pregnancy.16 That study included few women with early menarche and had therefore limited statistical power. In agreement with our findings, a retrospective study of 153 Norwegian women with persistent pelvic girdle pain following parturition, reported a lower age at menarche compared with the previous estimates of age at menarche in the general female population.24 Early menarche has also been associated with operative delivery in first-time mothers.25 The authors of that study hypothesised that prolonged hormonal stimulation of the uterus before the first birth has a negative influence on uterine muscle function. These studies, although few, suggest an underlying pre-pregnancy hormonal influence on both joint and uterine muscle dynamics in pregnancy.

The associations of early menarche with PGS in our study suggest a link between hormonal factors and pelvic girdle pain, and early menarche may indicate high estrogen levels.11,13,26,27 High estrogen levels in pregnancy may induce remodelling of connective tissue and increase joint mobility.7,8,28,29 Increased joint mobility may cause pain. Although a recent systematic review suggests an association between increased pelvic joint mobility and pelvic girdle pain,5 the evidence is limited.

During pregnancy, estrogens are mainly produced in the placenta, but an association of estrogen levels during pregnancy and pelvic girdle pain has not been found.30 An association of high estradiol levels with general joint pain during pregnancy has however been reported.31 The main objective of that study was to assess the potential relationship between maternal hormonal levels and joint laxity changes during and after pregnancy, but no correlations between estradiol levels and joint laxity changes were found. The association of early menarche with PGS suggests an influence of pre-pregnancy hormonal factors rather than hormonal factors during pregnancy. To our knowledge, a possible relationship between pre-pregnancy hormonal levels and pelvic girdle pain in pregnancy has not been studied.

Long duration of estrogen exposure before pregnancy could be associated with the development of PGS. Furthermore, the time interval between menarche and the index pregnancy may serve as an indicator of duration of exposure. Although women with early menarche had a longer time interval between menarche and the index pregnancy, our findings do not support an association of PGS with duration of estrogen exposure because younger mothers had a higher risk of PGS than older mothers.

Sex hormones are important for closure of the epiphyseal growth plates, and early menarche has been associated with the size of the pelvic girdle at puberty.32,33 The timing of menarche may therefore influence the structural and biomechanical development of the pelvic girdle and thereby the adult pelvic size and function. Although women with early menarche have higher BMI34,35 and may be shorter than women with late menarche,25,35 an association of adult pelvic diameters with age at menarche has not been found.36

We identified high BMI as an independent risk factor for PGS. The high weight in women with high BMI may strain the pelvic girdle and thereby increase the risk of developing pain. Women with high BMI may, however, also have increased levels of estrogens because adipose tissue is a source of estrogens.15 Also, early menarche in combination with adult overweight has been associated with high estrogen levels throughout the menstrual cycle.37

Pregnancy is a state in a woman’s life when vulnerability to disease may appear for the first time.38 Most pain conditions are associated with increased sensitivity to pain.39 Hence, normal pregnancy changes in the pelvic girdle may be painful only to women with increased pain sensitivity. Estrogen levels have been associated with increased pain sensitivity,40 and early menarche has been associated with musculoskeletal pain in women;14 however, the evidence is contradictory and the possible mechanisms are unclear.

Conclusions

We found that early menarche was associated with increased prevalence of PGS in pregnancy. Our findings suggest that factors associated with early menarche play a role in the development of pelvic girdle pain in pregnancy.

Disclosure of interests

None.

Contribution to authorship

All authors planned the study and performed the analysis. EKB, MEG and AE wrote the major part of the paper. EKB, MEG, CSN and AE discussed the design, edited the paper, and agreed on the final version. 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 analysis.

Details of ethics approval

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.

Funding

The Norwegian Mother and Child Cohort Study is supported by the Norwegian Ministry of Health, NIH/NIEHS (grant no. N01-ES-85433), NIH/NINDS (grant no. 1 UO1 NS 047537-01), and the Norwegian Research Council/FUGE (grant no. 151918/S10). The present study was supported by the Norwegian Research Council.

Acknowledgements

The authors thank Eli Heiberg for assistance in initiating this project and for valuable advice and support.

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