Materials and Methods
This was a planned supplementary analysis of data collected for the Mothers’ Outcomes after Delivery (MOAD) study, a longitudinal cohort study of maternal health outcomes after childbirth. The study began recruitment in 2008 and is ongoing. The study details have been previously described. Briefly, women are recruited 5-10 years after delivery of their first child at Greater Baltimore Medical Center. Recruitment is based on delivery type (cesarean without labor, cesarean with labor, vaginal birth) and matched for maternal age and years since delivery. As previously reported, participation in this research was similar across birth groups. Participants are seen on an annual basis at which time a physical examination is performed and questionnaires are completed. Institutional review board approval was obtained for this research and all participants provided informed consent.
Questions about pelvic pain are asked at the first follow-up MOAD visit, approximately 1 year after a woman’s baseline visit, and 6-11 years after her first delivery. The Oxfordshire Women’s Health Study Questionnaire is used to assess prevalence, severity, and frequency of pelvic pain. The questionnaire is a validated tool and has previously been used to study gynecologic pain populations. At the time of this analysis, 1497 women were enrolled in the MOAD study, and 1416 (95%) were eligible for the first follow-up survey. Among those who were eligible, 1129 (80%) completed the survey (including the Oxfordshire Questionnaire), 230 (15%) did not participate in this follow-up study, and 57 (4%) were still pending at the time of this analysis. Of the 1129 completing the survey, 14 women were excluded from the analysis because they reported having surgery for pelvic pain prior to their first delivery, leaving 1115 for the analysis.
The primary outcome for this analysis was moderate or severe pelvic pain as determined by the Oxfordshire Questionnaire. The questionnaire explores 3 types of pelvic pain: dysmenorrhea (pain associated with menses), dyspareunia (pain associated with sexual intercourse), and pelvic pain not associated with menses or intercourse. Women who are still menstruating are asked about dysmenorrhea. Those who report dysmenorrhea are asked how often the painful periods occurred over the past year: never, occasionally (with <25% of periods), often (with 25-50% of periods), usually (with >50% of periods), or always (with every period). They are also asked to classify their pain as none, mild, moderate, or severe. Women who report having intercourse in the past year are asked similar questions regarding dyspareunia. In addition to the frequency and severity questions, women reporting dyspareunia are asked whether their pain occurred during intercourse, in the 24 hours after intercourse, or both during and in the 24 hours after intercourse. All women participating in the survey are asked about pelvic pain not associated with menses and intercourse, and those who report having pain are asked to classify the severity of their pain in the same fashion as mentioned above.
The main exposure of interest was vaginal birth. Women who had at least 1 vaginal delivery were compared with women who delivered all of their children by cesarean. The delivery records for every Greater Baltimore Medical Center delivery were reviewed by a MOAD physician and the following obstetrical exposures were recorded: vaginal birth, prolonged second stage (>2 hours), vaginal delivery with birthweight ≥4000 g, perineal laceration, episiotomy, anal sphincter laceration, and operative vaginal delivery (vacuum or forceps). The 1115 women in this analysis contributed 2126 delivery records to the study; of those, only 107 (5%) deliveries occurred at outside hospitals. In cases where the woman delivered somewhere other than Greater Baltimore Medical Center or the information was missing on the chart, the woman’s self-reported history was used. In addition to the obstetrical exposures, we also considered the following confounders: age at first follow-up, years from first delivery to first follow-up, race, maternal age at first delivery, multiparity, and obesity at time of first follow-up. Obesity was defined as a body mass index (BMI) of ≥30 kg/m 2 .
To compare maternal characteristics by mode of delivery, P values were calculated using a Fisher exact test for categorical variables and a Kruskal-Wallis test for continuous variables. The χ 2 tests were run to detect differences in pelvic pain prevalence, severity, and frequency by mode of delivery. To identify differences in prevalence of moderate to severe pain by maternal characteristics and obstetrical exposures, we used multivariate logistic regression, modeling pelvic pain on the characteristic of interest, age >40 years and BMI ≥30 kg/m 2 . All analysis was performed using SAS 9.2 statistical software (SAS Institute, Cary, NC). Statistical significance was defined at the α = 0.05 level.
Results
In all, 1115 women completed the first follow-up visit and are included in this analysis. There was no difference in participation between women who had delivered vaginally vs those who had delivered exclusively by cesarean. In all, 577 delivered by cesarean only and 538 had at least 1 vaginal birth. The maternal characteristics, by delivery group, are listed in Table 1 . Women who delivered by cesarean were significantly more likely to be obese, and women with at least 1 vaginal delivery were more likely to have experienced a prolonged second stage of labor. Of those women who experienced at least 1 vaginal birth, 14% (75) delivered at least 1 infant ≥4 kg vaginally, 62% (331) had at least 1 perineal laceration, 55% (297) had at least 1 episiotomy, 18% (99) had at least 1 anal sphincter laceration, and 25% (132) had at least 1 operative delivery (data not shown).
| Characteristic | Cesarean delivery only (n = 577) | At least 1 vaginal birth (n = 538) | P value |
|---|---|---|---|
| Age at first follow-up, y | 39.8 (36.7–44.0) | 40.1 (36.6–43.6) | .649 |
| Time from first delivery, y | 7.8 (6.9–9.6) | 7.8 (6.8–9.6) | .990 |
| African American race | 16% (91) | 12% (63) | .056 |
| Maternal age >35 y at first delivery | 28% (159) | 25% (137) | .456 |
| Multiparity | 70% (401) | 77% (415) | .005 |
| BMI ≥30 kg/m 2 at first follow-up | 34% (196) | 18% (99) | < .001 |
| History of prolonged second stage | 18% (104) | 28% (148) | < .001 |
Pelvic pain by mode of delivery is summarized in Table 2 . Women who delivered by cesarean only were more likely to report moderate to severe dysmenorrhea ( P = .020). We found no other significant differences between delivery groups in the prevalence or severity of pelvic pain. Eighty-one women (7%) experienced both a vaginal and cesarean delivery, and therefore would carry risk factors for both types of deliveries. In a separate sensitivity analysis that excluded these 81 women, our primary conclusions were unchanged.
| Pain | Mode of delivery | P value | |
|---|---|---|---|
| Cesarean delivery only (n = 577) | At least 1 vaginal birth (n = 538) | ||
| Dysmenorrhea a | |||
| No longer menstruating | 86/558 (15%) | 55/521 (11%) | .056 |
| Menstruating without pelvic pain | 242/558 (43%) | 245/521 (47%) | |
| Menstruating with pelvic pain | 230/558 (41%) | 221/521 (42%) | |
| Among menstruating women | |||
| Pelvic pain occurs often, usually, or always | 148/472 (31%) | 126/466 (27%) | .152 |
| Moderate/severe pain | 134/472 (28%) | 101/466 (22%) | .020 |
| Dyspareunia b | |||
| No intercourse in past year | 30/559 (5%) | 24/513 (5%) | .866 |
| Intercourse without pelvic pain | 409/559 (73%) | 380/513 (74%) | |
| Intercourse with pelvic pain | 120/559 (21%) | 109/513 (21%) | |
| Among women who had intercourse in past year | |||
| Pelvic pain occurs often, usually, always | 32/529 (6%) | 38/489 (8%) | .322 |
| Decreased frequency of intercourse due to pain | .722 | ||
| Yes | 36/529 (7%) | 28/489 (6%) | |
| Not sure | 8/529 (2%) | 9/489 (2%) | |
| Timing | .834 | ||
| Pelvic pain during intercourse | 50/529 (9%) | 50/489 (10%) | |
| Pelvic pain after intercourse | 28/529 (5%) | 27/489 (6%) | |
| Pelvic pain both during and after intercourse | 42/529 (8%) | 32/489 (7%) | |
| Moderate/severe pain during intercourse | 30/529 (6%) | 23/489 (5%) | .573 |
| Moderate/severe pain after intercourse | 20/529 (4%) | 10/489 (2%) | .137 |
| Pelvic pain not associated with menses or intercourse c | 120/555 (22%) | 87/515 (17%) | .053 |
| Moderate/severe pain | 30/555 (5%) | 24/515 (5%) | .675 |
a n = 36 women were not sure if they experienced pelvic pain with periods and were excluded from dysmenorrhea portion of table
b n = 43 women were not sure if they experienced pelvic pain during or after intercourse and were excluded from dyspareunia portion of table
c n = 45 women were not sure if they experienced pelvic pain not associated with menses or intercourse and were excluded from unassociated pain portion of table.
Overall, dysmenorrhea was common in our population with 42% of women reporting pain with menses. Dyspareunia was also relatively common (21%), however, very few women reported moderate to severe dyspareunia or a decrease in frequency of intercourse due to dyspareunia. In all, 191 (17%) women had talked to a health care provider about pain, and 19 women (2%) reported having surgery for pelvic pain. The median age of women at the time of their surgery was 36 years (interquartile range, 32–39), with no difference noted between groups for prevalence or age at surgery.
Moderate to severe pelvic pain based on maternal and obstetrical characteristics is presented in Table 3 (adjusted for age >40 years and BMI ≥30 kg/m 2 ). Dysmenorrhea was reported more frequently by younger and obese women and less frequently among women using hormonal contraception. Although moderate or severe dysmenorrhea was significantly more common among women who delivered by cesarean ( Table 2 ), this relationship loses significance after adjusting for age and obesity ( Table 3 ). In a post hoc analysis, our study had had 80% power to detect a ≥9% difference in dysmenorrhea. Among those who had at least 1 vaginal birth, moderate to severe dyspareunia was more common among those who experienced a vaginal delivery of a baby ≥4 kg and those who had at least 1 forceps delivery. Moderate or severe pain unrelated to menses or intercourse was not associated with any of the maternal or obstetrical characteristics studied.
| Characteristic a | Moderate or severe dysmenorrhea (n = 938 b ) | Moderate or severe dyspareunia during and/or after intercourse (n = 1018 c ) | Moderate or severe pelvic pain unrelated to periods or intercourse (n = 1070 d ) | |||
|---|---|---|---|---|---|---|
| Overall | 25% (235/938 b ) | 7% (69/1018 c ) | 5% (54/1070 d ) | |||
| % (Yes/total) | P value e | % (Yes/total) | P value e | % (Yes/total) | P value e | |
| Primary race | .459 | .843 | .491 | |||
| Caucasian/other | 25% (199/811) | 7% (58/875) | 5% (47/923) | |||
| African American | 28% (36/127) | 8% (11/143) | 5% (7/147) | |||
| Maternal age >35 y at first delivery | .361 | .252 | .465 | |||
| Yes | 18% (43/233) | 7% (19/263) | 5% (14/286) | |||
| No | 27% (192/705) | 7% (50/755) | 5% (40/784) | |||
| Hormonal contraception use | .008 | .096 | .231 | |||
| Yes | 17% (27/162) | 4% (7/177) | 3% (6/181) | |||
| No | 27% (208/776) | 7% (62/841) | 5% (48/889) | |||
| Multiparous | .932 | .261 | .852 | |||
| Yes | 25% (176/703) | 6% (47/748) | 5% (40/782) | |||
| No | 25% (59/235) | 8% (22/270) | 5% (14/288) | |||
| Obstetrical exposure group | .147 | .249 | .783 | |||
| Cesarean only | 28% (134/472) | 8% (41/529) | 5% (30/555) | |||
| At least 1 vaginal birth | 22% (101/466) | 6% (28/489) | 5% (24/515) | |||
| Prolonged second stage f | .420 | .178 | .403 | |||
| Yes | 21% (44/214) | 8% (19/233) | 5% (13/247) | |||
| No | 25% (137/550) | 6% (34/590) | 4% (27/616) | |||
| Vaginal delivery of baby ≥4 kg ever g | .608 | .036 | .325 | |||
| Yes | 19% (12/64) | 11% (8/70) | 7% (5/73) | |||
| No | 22% (89/402) | 5% (20/419) | 4% (19/442) | |||
| Perineal laceration ever g | .542 | .009 | .720 | |||
| Yes | 23% (65/286) | 4% (11/307) | 4% (14/318) | |||
| No | 20% (36/180) | 9% (17/182) | 5% (10/197) | |||
| Episiotomy ever g | .065 | .347 | .365 | |||
| Yes | 18% (48/265) | 7% (18/268) | 4% (11/286) | |||
| No | 26% (53/201) | 5% (10/221) | 6% (13/229) | |||
| Anal sphincter laceration ever g | .618 | .199 | .803 | |||
| Yes | 19% (17/89) | 9% (8/92) | 4% (4/97) | |||
| No | 22% (84/377) | 5% (20/397) | 5% (20/418) | |||
| History of operative deliveries g | .384 | .006 | .802 | |||
| Spontaneous only | 21% (76/356) | 4% (16/367) | 5% (18/387) | |||
| Vacuum without forceps | 21% (10/48) | 4% (2/52) | 4% (2/53) | |||
| At least 1 forceps delivery | 24% (15/62) | 14% (10/70) | 5% (4/75) | |||
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