The Basis for using Palpation of the Cervix as a fertility indicator
During the fertile phase of the cycle certain parameters of the cervix change, e.g. its position, texture and the width of the cervical os. These changes are the basis of its use as a fertility indicator and can be observed by the woman herself when she learns how to palpate the cervix.1
The Natural Family Planning teacher must teach the woman how to palpate the cervix and to chart the cervix observations. Palpation of the cervix is easy to learn and after charting her observations for three cycles the woman will become confident in her observations.
When is the cervix observation done?:
Palpation of the cervix is done once a day in the evening. Palpation of the cervix as afertility indicator is never used alone, but only in conjunction with another fertility indicator such as basal body temperature (BBT) or cervical mucus.
CHANGES IN THE POSITION OF THE CERVIX IN THE FERTILE PHASE (2)
The cervix in the fertile phase 2:During the fertile phase the cervix moves upwards away from the vaginal opening and around the time of the ‘peak’ mucus symptom, at the time of maximum fertility, the cervix reaches its highest point making it difficult to reach with the finger. This is called the maximum cervix position. During the fertile phase the cervix becomes progressively softer and feels wet due to the presence of mucus and the cervical os* will gradually opento admit a finger tip and will be at its maximum width at ovulation. These changes are due to the action of oestrogen.
Any change in position or in consistency of the cervix from its original infertile state indicates the start of the fertile phase2 and usually corresponds with the beginning of the mucus symptom. (*The external opening of the cervix is called the ‘cervical os’.) (LINK to 6e for Fig. 6-16 to see the position of the cervical os) (LINK to Fig. 24-1 anatomy)
CHANGES IN THE POSITION OF THE CERVIX IN THE INFERTILE PHASE
The cervix in the infertile phase: During the infertile phases of the menstrual cycle both before and after the fertile phase, the cervix is low and is easier to reach, it feels firm and dry as the mucus has dried up, and the cervical os is closed. These changes are due to the action of progesterone. The change of the cervix from its ‘maximum’ position with an open cervical os, to a low position and a closed cervical os is abrupt, and it usually occurs on the day following the ‘peak’ mucus symptom.
HOW LONG DOES IT TAKE TO BECOME FAMILIAR WITH THE CHANGES IN THE CERVIX?
It usually takes about two or three cycles for the woman to become familiar with these changes in the cervix. The ‘palpation of the cervix’ indicator can be used in combination with either the Basal Body Temperature or the cervical mucus symptom, as one of the two fertility indicators required to define the beginning and/or the end of the fertile phase of the cycle. Its use is defined by the RULES of the symptothermal double-check method of Natural Family Planning and the woman must be taught these rules by a qualified Natural Family Plannning teacher.
At certain times during the woman’s child-bearing years observation of changes in the cervix is a very useful fertility indicator when other fertility indicators may be difficult to interpret due to the hormonal changes occurring in the body such as in the pre-menopause and after child-birth.2 (In the pre-menopause when fertility is declining, cycle lengths may be irregular and the cervical mucus symptom unreliable, and after child-birth when fertility is returning, cycle lengths may be longer, and the Basal Body Temperature may be erratic).
- Keefe, E.; ‘Self-observation of the cervix to distinguish days of possible fertility'; Bull of the Sloane Hosp for Women; 1962; 129-136
- Flynn A, Brooks M; ‘The Manual of Natural Family Planning'; pages 74-80; 1996; ISBN 0 7225 3115 X