Fertility Awareness (7)

Natural Family Planning and irregular cycles:

Women with regular or irregular cycles can use natural family planning to identify when they are potentially fertile once they have learned to recognise the changes in the fertility indicators, e.g. cervical mucus, basal body temperature, during the cycle, (fertility awareness).

Fertility Awareness means that the woman, by self-observation of the various signs and symptoms recurring during the menstrual cycle, can identify the fertile and infertile phases of the cycle herself irrespective of cycle length.(4) These signs and symptoms have a physiologic and scientific basis (6) and are due to the effects of the varying levels of the ovarian hormones oestrogen and progesterone on the fertility indicators during the cycle. The most important fertility indicators are the cervical mucus and the basal body temperature (BBT).

The fertility indicators are :

The woman may also find other fertility indicators of a minor nature useful, such as the calendar calculation, (Link to 14) and the presence of various symptoms (called molimina) e.g. ovulation pain (mittelschmertz) or breast symptoms.

When is the Fertile Phase of the menstrual cycle and how long does it last? : The Fertile Phase of the cycle includes the time when the mature ovum is available for fertilization at ovulation and the 6 days or so leading up to ovulation when oestrogenic fertile-type cervical mucus is present. The fertile phase is the combined time of the lifespan of the ovum after ovulation, (24 hours), and the lifespan of sperm in fertile-type mucus before ovulation, (5 days).1,2 Therefore the fertile phase during which sexual intercourse could potentially result in conception lasts for 6 - 9 days.7 (LINK to 6d fertility cycle) (LINK to 11b mucus).

References:

  1. Wilcox AJ, Weinberg CR, Baird DD; ‘Timing of sexual intercourse in relation to ovulation - effects on the probability of conception, survival of the pregnancy, and sex of the baby’; N Engl J Med 1995; 333;1517-21.
  2. Simpson JL; Editorial, Pregnancy and the timing of Intercourse; N Engl J Med 1995; 333;1563-64.
  3. Marshall, J; A field trial of the basal body temperature method of regulating births; Lancet,1968,July, 8-10;
  4. Billings, E & J; Symptoms & Hormonal Changes accompanying ovulation; Lancet; Feb5; 1972; 282-284.
  5. Keefe, E.; ‘Self-observation of the cervix to distinguish days of possible fertility’; Bull of the Sloane Hosp for Women; 1962; 129-136.
  6. Moghissi KS, Syner FN, Evans TN: ‘A composite picture of the menstrual cycle’; Am J Obstet Gynecol, 1972; 114:405- 418.
  7. Freundl G, Godehardt E, Kern PA, et al; “Estimated maximum failure rates of cycle monitors using daily conception probabilities in the menstrual cycle”; Human Reproduction, (2003), vol 18, no. 12, p2628-2633.

To be most effective, the woman must be taught the Symptothermal Double-Check Method of Natural Family Planning by a qualified natural family planning teacher.