Cervical secretion methods in natural family planning

Cervical Secretion Methods

• cervical secretion characteristics are highly predictive of ovulation and can therefore be used to avoid pregnancy
• studies conducted by the World Health Organization indicate that 93% of women, regardless of their education level, are capable of identifying and distinguishing fertile and infertile cervical secretions
  
  
• all the methods involve noting the presence or absence of cervical secretions, usually recommended to be checked both at midday and early evening when women are less likely to have sex
  • women are asked to characterize the secretions as to colour, texture, and stretch, the detail depending on the method of instruction
  • fertile cervical secretions - clear, wet, slippery, stretching and changing in quality (often compared with egg whites)
  • infertile secretions - unchanging and generally dry, sticky, cloudy, and do not stretch
  • menstruation is considered fertile because menses can mask the signs of cervical secretion, as can sexual fluids
    • therefore, a day of abstinence after coitus occurring between menstruation and ovulation is required to interpret secretion signs
    • hence, every other day between menstruation and the onset of the fertile phase is available for intercourse
  • peak fertility is identified retrospectively when fertile secretions begin to return to a basic infertile pattern
    • safe to have intercourse without restrictions on the fourth day after peak fertility until the onset of the next menses
  • any bleeding or cervical changes that interrupt the basic infertile pattern are potentially fertile
    
    
• Billings Ovulation Method (BOM)
  • allows women to describe secretions 'in their own words' with a focus on changes in cervical characteristics
    • in a study undertaken in India, pregnancy rates among perfect and all users of this method were 1.1% and 2% to 10.5%, respectively, at 12 months
    • the World Health Organization study of 1981 calculated typical-use pregnancies of 22.3%, with 15.4% caused by a conscious departure from method rules
      
      
• Creighton Model
  • a distinct method, the Creighton Model (CrM), also called NaProTechnology, is more standardized in the way secretions are characterized, using pictures and precise words to describe them than the Billings Ovulation method
    • male partner is responsible for charting and interpreting the data
    • effectiveness of the CrM has improved since its introduction in 1980, presumably because of improved methods of instruction
    • CrM users are instructed that conscious departure from the method rules resulting in intercourse on method-predicted fertile days implies that they are no longer using the method for avoiding pregnancy but for achieving pregnancy
      • all pregnancies resulting from such actions are thus classified as achieving-related pregnancies without distinguishing between intended or unintended pregnancies
        
        
• two day method (TDM)
  • simpler method than BOM and CrM
  • woman is taught to identify cervical secretions of any type regardless of their characteristics
    • she then is instructed to ask herself
      • 'Did I notice any cervical secretions today?'
        • if the answer is no, she then asks, 'Did I notice any cervical secretions yesterday?'
          • if the answer is no, then intercourse is unlikely to result in pregnancy
          • if the answer to either of the 2 questions is 'yes', then intercourse has a high probability of resulting in a pregnancy
    • same preovulatory cervical secretion check rules described above apply
    • there are no restrictions on coitus when cervical secretions meet the 2-days rule after peak fertility and until the onset of the next menstruation

Reference:

• 1) Pallone SR, Bergus GR.Fertility awareness-based methods: another option for family planning. J Am Board Fam Med. 2009 Mar-Apr;22(2):147-57.
• 2) Evans C.Natural family planning is effective and culturally acceptable.BMJ. 2012 Jul 23;345:e4908. doi: 10.1136/bmj.e4908.
• 3) Freundl G et al.State-of-the-art of non-hormonal methods of contraception: IV. Natural family planning. Eur J Contracept Reprod Health Care. 2010 Apr;15(2):113-23.