Fertility, Belief, and Sexuality

The human ovulatory cycle lasts an average of 28 days and is highly variable both within and among women, making ovulation and the fertile window difficult to estimate in humans. Commonly used methods for estimating fertility assume length consistency during various cycle phases, an assumption that often miscategorizes women as fertile when not and vice versa. This experiment analyzes several of the common methods used to estimate fertility, including forwards and backwards-counting methods and actuarial methods, and compares them against hormonal testing to determine the most accurate method for fertility identification. Additionally, we used hormonal ovulation tests combined with daily journaling reports to determine the degree to which fertility affects sexual desire, likely sexual engagement, and general happiness, as well as a woman’s belief that she is fertile. We hypothesize that women will not be able to accurately predict their fertility and will show increased sexual interest and general happiness during the fertile window. We also hypothesize that estimation methods will have different results than those using confirmed fertility, but that the closest estimation will be backward counting methods estimating fertility as the six-day window ending at thirteen days from the start of menses