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For further information, see CMDT Part 18-12: Contraception

Key Features

  • Periodic abstinence during fertile periods

    • Most effective when intercourse restricted to postovular phase of cycle or barrier method used at other times

    • Women should identify fertile periods (see Infertility, Female)

  • "Symptothermal" natural family planning

    • Patient-observed increase in clear elastic cervical mucus, brief abdominal midcycle discomfort ("mittelschmerz")

    • Unprotected intercourse is avoided from shortly after the menstrual period until 48 h after ovulation, as identified by a sustained rise in temperature and the disappearance of clear elastic mucus

  • In the calendar method, after the length of the menstrual cycle has been observed for at least 8 mo, the following calculations are made

    • The first fertile day is determined by subtracting 18 days from the shortest cycle

    • The last fertile day is determined by subtracting 11 days from the longest cycle

  • Basal body temperature method shows the safe time for intercourse after ovulation has passed

    • Take temperature immediately upon awakening, before any activity

    • A slight drop in temperature often occurs 12–24 h before ovulation, and a rise of about 0.4°C occurs 1–2 days after ovulation

    • The risk of pregnancy increases starting 5 days before the day of ovulation, peaks on the day of ovulation, and then rapidly decreases to zero by the day after ovulation

  • The Standard Days Method

    • Uses a set of beads to remind the couple to avoid intercourse during days 8 through 19 of the cycle

    • Typical use failure rate may be about 12%

  • The TwoDay Method

    • Requires that women be able to identify cervical secretions by observation or touching them in underwear or toilet paper, by touching the genitals, or by the sensation of wetness in the genital area or on underwear

    • The woman then uses a two-question algorithm to determine if she is fertile

    • She asks herself:

      • Did I note secretions today?

      • Did I note secretions yesterday?

    • If the answer to either of these questions is "yes," she should consider herself fertile

    • In a multicenter study of 450 women, effectiveness with perfect use was 96.5% and with typical use 76.3%

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