The Justisse Method is 99.4% effective to avoid pregnancy with perfect use.
Perfect use to avoid pregnancy means that the woman charts her cycles strictly according to the Justisse Methodology and strictly observes the rules for avoiding pregnancy set out by the method.
If barrier methods or the withdrawal method are used on fertile days the effectiveness to prevent pregnancy becomes that of the barrier or withdrawal method, from about 70% to 80%.
The Justisse Method chart completed according to the method's system for observation and charting is a valuable and valid document for assessing reproductive health, and for making informed decisions about the necessity of using emergency contraception should an act of unprotected intercourse, after the fact, suggest the risk of pregnancy.
The effectiveness of fertility awareness to help couples avoid or achieve pregnancy or monitor gynaecological and reproductive health, depends on a woman being taught to observe, chart and interpret the three primary signs of fertility: cervical mucus secretions, basal body temperature and cervical position by a skilled educator such as a Justisse Practitioner.
The Justisse Method client teaching and charting system are based on the Creighton Model and there for users may expect a similar effectiveness.
Research on the effectiveness of fertility awareness methods for birth control?
According to the World Health Organization, 93% of women everywhere can identify the symptoms which distinguish adequately between the fertile and the infertile phases of the [menstrual] cycle…[Using fertility awareness for reproductive planning] is inexpensive, cost effective, without side effects …-- British Medical Journal. Vol. 307, 18 Sept. 1993. This research was conducted using the Ovulation Method with no accommodation for the use of barrier methods or alternative sex practices during the fertile phase. More research on effectiveness