The menstrual cycle is driven by changes in estrogen and progesterone levels. The menstrual cycle is split into the follicular phase and luteal phase. During the follicular phase, the egg from the previous cycle is unfertilized and the uterine lining is shed during menstruation. Estrogen and progesterone are at their lowest. A new uterine lining is then produced along with a sharp peak in estrogen. In the luteal phase, ovulation is triggered and progesterone and estrogen levels rise. 

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Previous studies have linked increased estrogen and progesterone levels to decreased gut motility, the time it takes for food to move through the digestive system. 

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Team BELI will be using the smart underwear in order to track transit time in females during days 1-3, 12-14, and 21-24 of their menstrual cycle.

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