This new edition for the twentieth anniversary of the groundbreaking national bestseller provides all the information you need to monitor your menstrual cycle�

Doctor Billings, who researched and formulated the ovulation method, explains its use.

Explains the fertility cycle and how conception occurs. Discusses how pregancy can be prevented by using the Billings method (Ovulation method).

The "contraceptive revolution" of the 1960s and 1970s introduced totally new contraceptive options and launched an era of research and product development. Yet