What fertility indicator is best to help achieve pregnancy:
The only fertility indicator that tells the woman when she is potentially fertile is the mucus symptom. In order to achieve pregnancy the woman should therefore become familiar with her own personal cervical mucus pattern.
The woman who has learned to observe and record the changes in cervical mucus during her cycle can identify when she is fertile, and can use this knowledge to achieve pregnancy by planning intercourse at the time of her maximum fertility according to the mucus symptom.
She can identify when the fertile phase begins by the presence of mucus at the opening of the vagina either by the sensation it causes there, or by observing its appearance as she can see the mucus on white toilet paper when she wipes herself before and after she passes urine. The mucus discharge is present for six days immediately before ovulation and it dries up after ovulation.
The mucus ‘build-up’ to Peak day during the six days before ovulation:
In an average cycle when the menstrual period has finished, the woman notices that she has a sensation of dryness at the opening of the vagina, (called the vulva) which lasts 2 or 3 days. Then over the following six days she notices the ‘build-up’ of mucus at the vulva.
She first notices the presence of mucus as a sensation of moistness or dampness at the opening of the vagina and she observes that the mucus has a thick and opaque appearance. Then two or three days later the mucus changes to a wet, slippery, lubricative sensation at the vulva; it is now more copious and has a clear, stretchy, raw-egg-white like appearance, which is present for the next 2 or 3 days ending on ‘Peak’ day. The presence of this stretchy mucus with the slippery sensation indicates the time of maximum fertility but the presence of any mucus is a sign of potential fertility.
The last day of slipperiness is called Peak dayand it can only be identified in retrospect when there has been a definite change to a sensation of dryness at the vulva or to an absence of mucus at the vulva. Maximum fertility occurs at the time of ovulation when the ovum is released from the ovary into the fallopian tube and is available for fertilization. It has been shown that Peak day is closely related to the day of ovulation.1,2 The life span of the ovum after ovulation is 24 hours, but despite this brief life-span of the ovum, nature has designed that the fertile phase of the woman’s cycle is increased by the ability of sperm to survive in stretchy clear mucus, (S mucus) for up to 5 days.
When is the optimum fertile time?
Therefore to achieve pregnancy intercourse should occur on the days when there is a sensation of slipperiness at the vaginal opening and the mucus has a stretchy, clear appearance like raw-egg-white, or when the sensation of slipperiness is present and little or no mucus is present at the vulva.
The presence of stretchy slippery mucus, (called S mucus) is essential to achieve pregnancy, as it transports and nourishes sperm. Even if the woman is ovulating she cannot get pregnant without the presence of fertile-type S mucus.
In the case of women who have difficulty recognising the mucus symptom the couple should use the days when there is any sign of mucus at the opening of the vagina such as a sensation of moistness even if short lived. Pregnancy cannot occur without mucus but only a tiny amount of mucus is required and such a small amount of mucus may have escaped observation, hence the importance of observing the sensation as well as the appearance of mucus. In fact to achieve a pregnancy the couple should use any or all of the days that a sensation of moistness, wetness or slipperiness is present at the vulva, or when mucus itself is observed at the vulva.
The World Health Organization in a study of the ‘Ovulation Method’ of NFP found that 90% of women were able to distinguish their mucus pattern during the first cycle.5
If the mucus symptom is difficult to define:
For those women whose mucus symptom is unclear, modern technology has developed various cycle monitor devices to aid in the detection of ovulation which the woman can use at home. One such is a home kit to measure the levels of luteinizing hormone (LH) in the urine daily, and is a reliable way to detect ovulation.4
Does intercourse at the fertile time always result in pregnancy?
The answer is NO. Wilcox et al, in their article in the New England Journal of Medicine in 1995, found that conception occurred only when intercourse took place during the six-day period that ended on the estimated day of ovulation. The probability of conception ranged from 10% when intercourse occurred five days before ovulation to 33% when it occurred on the day of ovulation itself.(3) What is interesting in their study is that even when intercourse occurred when everything seemed ‘right’ in a particular cycle, 63% of women did not conceive. Wilcox et al also found that there was no support for a recommendation that normal couples seeking pregnancy should limit the frequency of sexual intercourse.3
Is the temperature chart any help in achieving pregnancy?
The Temperature Chart can tell the woman that she has or has not ovulated, and can confirm pregnancy. However by the time the thermal shift, (which indicates ovulation), has occurred it is usually too late to use this as a sign of fertility as the ovum lives for just 24 hours and is only fertilizable for 12-16 hours within that 24 hour period. Therefore the mucus symptom before ovulation is the indicator of choice to help achieve pregnancy.
The woman who has learned to record and interpret the changes in her Temperature Chart during her cycle, can recognise from the Temperature pattern whether or not she is ovulating. This knowledge is reassuring to the couple who wish to achieve pregnancy but as the ovum lives for just 24 hours the thermal shift is of little use in planning pregnancy; the mucus symptom before ovulation is the indicator of choice for the woman who wishes to conceive. The temperature chart will also confirm pregnancy as a higher-phase temperature that stays elevated for 21 days or more after ovulation is indicative of pregnancy.
Women who wish to conceive after coming of the Pill:
Women are advised to defer pregnancy for three months after stopping the Pill, as it may take three months or more for all the synthetic steroid hormone to be excreted from the body. (see the section on ‘After stopping the Pill’).
WHEN IS MEDICAL REFERRAL INDICATED ?
If a couple has not achieved pregnancy following six months of regular intercourse during the fertile time of apparently normal cycles, they should consult their doctor.
- Flynn AM, Lynch SS; ‘Cervical mucus and identification of the fertile phase of the menstrual cycle’ page 658; Br J of Obstet &Gynec; August 1976; vol 83; 656-659.
- Hilgers TW, Abraham GE, Cavanagh D; ‘Natural Family Planning – 1. ‘The Peak Symptom and Estimated Time of Ovulation’ Obstet & Gynec Nov 1978, vol 52, no 5 p 575-582.
- Wilcox AJ, Weinberg CR, Baird DD; ‘Timing of sexual intercourse in relation to ovulation’; N Engl J Med 1995, 333, no.23 p 1517-21.
- Guida, M et al; “Efficacy of methods for determining ovulation in a natural family planning program; Fertil & Steril; vol 72, no 5, Nov 1999, p 900-904.
- World Health Organization; ‘A prospective multi-centre trial of the Ovulation Method of Natural Family Planning 1; The Teaching Phase’; Fertility & Sterility; vol. 36, no 2, Aug 1981; p152-158.