In trials method related pregnancy rates have ranged between 0% to 2.9%. In a recent trial in China 992 couples using the Billings Method were compared to 662 couples using the IUD. The method-related pregnancy rate amongst Billings users was zero and the total pregnancy rate was 0.5%. In studies up to the 1980s teaching related pregnancies ranged between 0% to 6%. Total pregnancy rates vary between 1 and 25%. Reasons for a higher total pregnancy rate include misunderstanding the method, risk taking, ambivalence toward pregnancy, and deciding to become pregnant.
John Billings, described as a "staunch Catholic", developed the method as a form of natural family planning in accordance with his religious faith. He was recognized with a Papal knighthood in life, and condolences for his death were given by the Pope. Billings strove to raise awareness of the significance of cervical mucus to fertility to all people, regardless of their religion.
Thomas Hilgers later created the Creighton Model FertilityCare System as a variation of the Billings method. While Hilgers describes his method as a "standardization" of the BOM, Billings and his wife disputed this claim in a position paper.
Independently in 1953, Dr. John Billings (1918–2007) discovered the relationship between cervical mucus and fertility while assisting the marriage consultant for the Melbourne Catholic Family Welfare Bureau. Some of the couples he worked with had serious reasons to postpone pregnancy, and followed the Catholic Church's teachings of only using natural methods of pregnancy avoidance. While Dr. Billings was familiar with the Calendar and Basal Body Temperature methods, he felt there was a need for something more flexible and more reliable. He embarked on a study of medical literature, and found the mid-19th- and early-20th-century references to cervical mucus and sperm survival. He instructed women using the Rhythm method to avoid intercourse also on all days, and for a few days after, they noticed vaginal discharge. This resulted in a dramatic decrease in unintended pregnancies among these couples.
In the early 1960s, Dr. James Brown took a position at the Royal Women's Hospital in Melbourne, Australia. Dr. Brown had earlier developed the first tests to measure oestrogen and progesterone, and he used these tests to assist Dr. Billings in further study of the relationship between cervical mucus and fertility. Dr. Evelyn Billings joined the research team in 1965. By the late 1960s, the rules for identifying fertile days had been established and teaching centers began to be set up around the world. The method was called the Ovulation Method, to emphasize that the central feature of a woman's fertility cycle was ovulation, rather than menstruation. In the 1970s, a committee of the World Health Organization renamed it the Billings Ovulation Method.
Scientific verification of the Billings Method is ongoing. Dr. James Brown continued to study ovarian activity until his retirement in 1985. Dr. Erik Odeblad was acquainted with the Billings Ovulation Method in 1977, and reported that his research into the activity of the cervix confirmed all the conclusions made by Dr. Billings. Dr. Odeblad's research into the cervix and cervical mucus also continued for many decades.
Billings Method teachers help women recognize and understand their signs of fertility. This can help in the early diagnosis and treatment of gynaecological disorders, and can contribute to a woman's reproductive health.