The Relationship Between Gut Motility and the Phases of the Menstrual Cycle

Abstract

Female reproductive hormones fluctuate significantly throughout the menstrual cycle, influencing gastrointestinal motility and function. These changes in gut motility contribute to gastrointestinal symptoms such as flatulence, diarrhea, and constipation. When transit time is faster, fewer carbohydrates are absorbed in the small intestine, leading to increased microbial fermentation and gas production in the large intestine. Given the established effects of reproductive hormones on gut motility, we hypothesized that we would detect increased gut microbial gas production during menstruation, when estradiol and progesterone are lowest and transit time is fastest. However, due to a lack of tools to measure gut microbial gas production longitudinally, the literature lacks a formal test of this hypothesis. Therefore, we used a novel tool, the Smart Underwear device, to measure gut microbial gas production as a proxy for intestinal transit time. Participants wore the device for a total of nine days over the course of one menstrual cycle. On device-wearing days, participants logged the meals they consumed. Additionally, participants used Luteinizing Hormone test strips in the middle of their cycle, approximately on day 14, to confirm ovulation timing and more precisely map menstrual cycle phases. We extracted and analyzed the data from our returned Smart Underwear devices to measure gut microbial gas production as an indicator of intestinal transit time at different phases of the menstrual cycle, providing the first longitudinal measurements of gut microbial gas production across the menstrual cycle. Initial findings suggest that microbiome activity varies significantly across phases, with heightened activity during ovulation. Our analysis revealed that higher concentrations of flatulence peaks occurred during the ovulation phase.