Ogino theory; rhythm method basis
Refers to the fertility-awareness theory developed by Kyusaku Ogino, which forms the basis of the rhythm method of contraception.
The Ogino theory is known as a method for estimating the day of ovulation.
Named after the Japanese gynecologist Kyusaku Ogino (荻野久作). The term combines his surname 荻野 with 学説 (theory).