Gynecology Book


Natural Family Planning

Aka: Natural Family Planning, Fertility Awareness Method, Symptothermal Method, Ovulation Method, Billings Method, Rhythm Method, Calendar Method, Fertility Tracking
  1. Indications
    1. Conception Planning (Fertility Tracking)
    2. Pregnancy Prevention ("Contraception")
      1. These methods are not recommended for reliable Contraception
  2. Contraindications
    1. Irregular Menstrual Cycle
    2. Partner does not support fertility window abstinence or protection
  3. Types: Methods of Natural Family Planning
    1. Modern Methods with better efficacy
      1. Ovulation Method Criteria (Billings Method)
        1. Cervical Mucus characteristics
      2. Symptothermal Method Criteria
        1. Cervical Mucus characteristics
        2. Basal Body Temperature
    2. Rhythm Method (Calendar Method)
      1. Standard Rhythm Method failure rates approached 20% and should be avoided
      2. However, smartphone applications (e.g. Natural Cycles, Clue Birth Control) have 6.5% failure rate
  4. Technique
    1. Review calendar history of 3-6 prior Menstrual Cycles
    2. Determine Ovulation time
      1. See Ovulation for specific findings
      2. Urine LH Kit (100% correlation)
        1. Detects Luteinizing Hormone surge
        2. Accurate and cost effective (e.g. $20 for 50 tests)
        3. Identifies 2 days in cycle most likely to conceive (start testing a few days before expected Ovulation)
        4. Predicts Ovulation before it occurs
      3. Cervical Mucus (48% correlation)
      4. Basal Body Temperature
        1. Identifies Ovulation after it has occurred (contrast with LH Kit)
      5. Electronic fertility trackers (e.g. Ava smart bracelet, Kegg Vaginal Sensor)
        1. Expensive (>$250 in some cases) and not clear they work any better than Urine LH
      6. Avoid ineffective methods
        1. Salivary Ferning
        2. Salivary B-glucuronidase activity
    3. Avoid unprotected intercourse for mid-cycle 7-14 days
      1. Approximately Cycle Days 9 to 19 would be higher risk
      2. At higher risk mid-cycle days
        1. Abstain from intercourse
        2. Use barrier Contraception
  5. Efficacy
    1. Pregnancy prevention rate (Abstinence planning)
      1. Calendar (Rhythm Method): 83% effective (avoid)
      2. Basal Body Temperature alone: 96.1% effective
      3. Cervical Mucus alone: 92.6% effective
      4. Symptothermal Method: 99.6% effective
    2. Intended pregnancy rate (Conception planning)
      1. Normal fertility: 66% pregnancy rate within 1 cycle
  6. Disadvantages
    1. Regular Menstrual Cycles required
    2. Offers no Sexually Transmitted Disease protection
    3. Requires significant Patient Education
  7. Management
    1. Provide education on Emergency Contraception
    2. Review Menstrual Cycle and Ovulation
    3. Review Menstrual Cycle calendar over 3-6 months
    4. Review non-coital sexual activity
    5. Review barrier Contraception
  8. References
    1. (2022) Presc Lett 29(2): 11
    2. Guida (1999) Fertil Steril 72:900-4 [PubMed]
    3. Stanford (1998) J Fam Pract 46(1):65-71 [PubMed]
    4. Ryder (1993) BMJ 307:723-6 [PubMed]

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