In this study, we found the experience of one or more GI symptoms was very common for healthy women both before and during menses. Not surprisingly, abdominal pain was quite frequent, but around one-quarter of the women also experienced bowel habit disturbance in the form of diarrhea. GI symptoms occurred at a similar rate in both the premenstrual phase and during menses. However, there was a higher prevalence of depressed mood and fatigue premenstrually, compared to during menses. As well, GI symptoms occurred disproportionately more frequently with depressive or anxious emotional symptoms than when those were not present, both prior to and during menses. This significant co-occurrence was also observed for fatigue.
Studies that have assessed the prevalence of various GI symptoms perimenstrually have generally concluded that GI symptoms were more common for those with GI disorders than for healthy women [1, 3, 14, 15]. It was evident in our study that GI symptoms were quite prevalent for healthy women as well, as over 70% experienced GI symptoms in conjunction with their menstrual cycle, even when potential gynecological symptoms such as bloating were excluded. Some studies focused just on menses, and when they included more than one phase, they tended to report more frequent GI symptoms during menses than other phases [3, 15], although one of these studies reported on intensity but not the prevalence of GI symptoms . Other prospective studies described abdominal pain, nausea, and bloating as the predominant GI symptoms, and found they tended to increase just before and during menstruation [1, 16, 17] consistent with our findings of a similar rate of GI symptom occurrence across the premenstrual and menses phases.
Bowel habit changes have not been as readily addressed, but Kane and colleagues  described equivalent rates of diarrhea (20%) and constipation (20%) premenstrually, and lower rates of altered bowel habit during menses (diarrhea 10%; constipation 2%) in their sample of healthy women. Two studies found that approximately one third of women experienced bowel habit changes during menses, with diarrhea being more common [1, 4]. We also found diarrhea (24-28%) to be more common than constipation (10-15%), regardless of the menses phase. The lower rates for the Kane study might relate to their recruitment approach as they posted ads on a university campus, whereas the other studies, including ours, recruited from outpatient clinics offering routine gynecological care.
There has been little work to examine potential predictors of GI symptoms in relation to menses. Our exploratory study identified that depressed mood, anxiety and fatigue were each significantly more likely to be associated with primary GI symptoms. Similarly, women who had a history of painful menses were also more likely to experience GI symptoms perimenstrually. Previous work assessing the relationship between GI symptoms and both enduring personality traits and acute psychological symptoms with GI symptoms during menstruation did not find any significant relationship . In that study, women who reported their GI symptoms were exacerbated during their menses did not differ in their psychological profiles from women who did not report these symptoms . Keisner and colleagues reported a significant association between premenstrual depressive symptoms and a number of physical symptoms, of which GI symptoms were included .
Depression, pain, and gut motility may share similar pathophysiological mechanisms including serotonin as an important neurotransmitter mediating those symptoms . A study that found women in the late luteal phase experienced reduced pain tolerance, using a cold pressor test, provides some evidence for somatic neural changes related to the timing within the cycle . There has also been consideration of the effect of hormonal activity in local tissue, with a recent study suggesting that physical symptoms, including GI symptoms, may indicate sensitivity to reproductive steroids, and that concurrent psychological symptoms may reflect neurological sensitivity to these steroids, at a peak point in the menstrual cycle . Prostaglandins may provide another pathophysiological link to understand the overlap between menstrual pain and gastrointestinal symptoms. Premenstrually, uterine prostaglandin production may mediate an inflammatory response characterized by pain, and during menses abnormally high levels of prostaglandins in menstrual fluid may induce abnormal uterine contractions and pain [17, 20]. In the gut, prostaglandins can cause smooth muscle contractions, as well as reduced absorption and induced secretion of electrolytes in the small bowel, all of which may enhance gastrointestinal pain and diarrhea . It is not known whether uterine prostaglandins are transported to the gut, or whether parallel changes in uterine and GI smooth muscle prostaglandin levels occur during menses . Further study will be necessary to determine pathophysiological mechanisms for mood changes within the cycle as well and the direction of the relationship of these changes between brain and GI function.
While these findings are preliminary, they suggest that clinicians should be aware of the heightened potential for co-occurring gastrointestinal and emotional symptoms perimenstrually, and could consider providing information to their patients to help normalize the experience. If the GI symptoms become troubling or problematic, it may be useful to consider prophylactic steps to alleviate the symptoms through use of medication or behavioral approaches, parallel to the approach used to manage gynecological symptoms during menses (e.g., analgesic medication for dysmenorrhea).
There are limitations to the study. It was exploratory in nature, aiming to assess the presence of GI and emotional symptoms perimenstrually using participant observation, with minimal participant burden. There were no validated scales that included all the symptoms of interest, so a brief history and symptom measure was developed for the study. This had the benefit of assessing the variables of interest using the same response scale, for ready comparison. However, the validity of the symptom measure was not established, and further, the duration and severity of symptoms could not be determined as the measure simply assessed presence/absence of symptoms. Subsequent investigation of potentially relevant variables identified in this preliminary study, such as depression, anxiety, and pain, should include validated measures. Second, participants reported their perimenstrual symptoms retrospectively, which increases the likelihood of recall bias. Nevertheless, it was a relatively brief recall period of the recent 3 ‘samples’ of their cycle, and it has been shown that asking about very recent events helps to minimize recall bias . In addition, the cross-sectional design of the study did not allow for any conclusions regarding direction of influence. A prospective approach using daily symptom diaries would be optimal for future studies. Finally, though we specifically recruited healthy premenopausal women, the experiences of healthy women presenting for care in a gynecology clinic may not be broadly generalizable to premenstrual women, many of whom do not seek or have access to regular gynecologic care.