gynecology and obstetrics
Fertility Awareness‒Based Methods of Contraception
Introduction
Fertility awareness–based methods of contraception involve tracking menstrual cycles and other physiologic signs (eg, cervical mucus) to estimate the timing of a woman's fertile window (the days before, during, and after ovulation when unprotected sexual intercourse may result in pregnancy). Although the ovum can be fertilized for only about 12 hours after ovulation, sperm can fertilize an ovum for up to 5 days after intercourse; as a result, intercourse almost 5 days before ovulation can result in pregnancy. Thus, fertility awareness‒based methods require abstinence from intercourse starting 5 days before ovulation. Several methods can be used to identify the time of ovulation and thus determine when abstinence is required. They include Standard days (calendar) method: Avoids intercourse on cycle days 8 through 12 Two-day (ovulation, or mucus) method: Based on evaluation of cervical mucus Symptothermal method: Uses a combination of basal body temperature, evaluation of cervical mucus, and abstinence during the fertile period The symptothermal method has a lower pregnancy rate with perfect use than the 2-day method or the standard days method (with or without cyclebeads). However, pregnancy rates with any of these methods are high with typical use, so these methods are not recommended for women who strongly want to avoid pregnancy. Thelactational amenorrhea methodis another method, which can be used postpartum if a woman is breastfeeding. Method Pregnancy Rate in First Year of Use With Perfect Use Pregnancy Rate in First Year of Use With Typical Use Standard days 5% 12% Two-day 4% 14% Symptothermal < 1% 2% 