How does the Calendar Method of natural family planning work?
This is the most common of the fertility awareness methods. Women will calculate the onset and duration of their fertile period based on several assumptions that: • ovulation occurs 12 to 16 days before the onset of the next menses, • sperm remain viable for two to three days and • the egg survives for 24 hours. Based on this method, a couple would avoid intercourse or use another contraceptive during an eight- to ten-day period in each cycle. The woman should chart a menstrual calendar over several months. Her fertile period is determined by subtracting 20 days from her shortest cycle (to establish when the fertile period begins) and subtracting 10 days from her longest cycle (to establish when the fertile period ends). Recent studies show that there may be a wider variation in the “fertile time” than traditionally calculated by this method-hence inadvertent pregnancies may result when this technique is used as a means to avoid pregnancy. The couple is not protected from sexually tran
