Concealed ovulation

Topic

Concealed ovulation, or hidden estrus, is the lack of any perceptible physical or behavioral changes in an adult female when she is fertile and near ovulation. Unlike species that exhibit obvious signs of fecundity, such as sexual swellings or pheromone release, humans and a few other species show few external indicators of fertility. This biological trait makes it difficult for mates to consciously detect when ovulation is occurring, which has significant evolutionary implications.