Outer ring of the female condom may slip into vagina during intercourse. Difficulty inserting the female condom . Similar prices for films and suppositories . Advantages No medical or hormonal side effects. Calendars, thermometers, charts easy to get.
Most religions accept periodic abstinence .
Possible Problems Uncooperative partners. Poor record keeping. Illness and lack of sleep affect body temperature. Vaginal infections and douches change mucus. Cannot use with irregular periods or temperature patterns.