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The physical act of intercourse (reserved only for marriage) is proper when it is an expression of love that is open to the possibility of new human life. An act of intercourse between a married man and woman is a true expression of love when there is a total giving of self. Total giving of self includes giving and receiving the gift of fertility. Any act of suppressing, blocking or destroying the gift of fertility or destroying new human life once begun is an act against love and life.

Sexuality is an integral and good part of human life. When used in an ordered (proper way), sexuality is life giving, integrative and unifying of human relationships. When not used properly (i.e., in a disordered way), sexuality retards human growth, destroys relationships and places an individual at high risk for disease and even death. Sexuality is ordered when expressed in a modest and chaste (non-genital or physical) way when a person is not married and is ordered when expressed chastely and physically between a man and woman who are married to each other.

When married couples have discerned that there is a need to space or limit children the means to do so must be truthful to love, the integrity of the sexual act and to the gift of fertility. As such, there are times within a woman’s monthly cycle that are fertile and times that are infertile. Natural Family Planning is a means in which a couple learns how to monitor the woman’s monthly cycle and to interpret the natural signs that tell them when the woman is fertile or not.

Natural Family Planning (NFP) is a general term that applies to various methods that have been developed to help women and men determine the fertile and infertile times of a woman’s menstrual (monthly) cycle. These methods can be used to achieve or avoid pregnancy. All of the methods rely on the interpretation of natural (biological) signs or indicators of fertility. Implicit in these methods are that couples abstain from intercourse, genital contact or withdrawal during the fertile time of the woman’s cycle if they are avoiding pregnancy. Use of any artificial means to interfere with fertility is not natural family planning.

There are four basic methods of natural family planning:

  1. The Calendar Method or (rhythm) – relies on counting cycle length and a simple formula to determine the beginning and end of fertility
  1. Basal Body Temperature (BBT) – recording of the woman’s daily waking temperature and observing the changing patterns
  1. The Ovulation Method (OM) – observing and recording the patterns and changes of cervical fluids
  1. The Sympto-thermal (ST) Method – combining daily waking temperature, changes in cervical fluid, cycle length and other minor signs of fertility.

Can I use breastfeeding as a natural family planning method?

Breastfeeding is also known as lactation. When used as a contraceptive method it can be very effective in avoiding pregnancy and is known as lactational amenorrhoea method (LAM). LAM can be up to 98 per cent effective in preventing pregnancy if all of the following conditions apply:

  1. Once you are fully breastfeeding – this means you are not giving your baby any other liquid or solid food or
  2. you are nearly fully breastfeeding – this means mainly breastfeeding your baby and infrequently giving your baby other liquids and
  3. your baby is less than six months old and
  4. You have no periods.
  5. The risk of pregnancy increases if:
  6. you start breastfeeding less often, or
  7. there are long intervals between feeds – both day and night, or
  8. You stop night feeds and use supplement feeding.

Once your baby is over six months old the risk of getting pregnant increases, so even if you don’t have periods and are fully or nearly fully breastfeeding, you should use another contraceptive method.

The term Natural Family Planning, however, usually refers to the two modern methods of natural family planning, i.e., the Ovulation Method (OM) and the Sympto-thermal (ST) method. Modern science and technology also has provided us with the means to accurately monitor other signs of fertility through electronic and chemical fertility devices. The Marquette Model of NFP applies these devices in helping the new learner of NFP to gain confidence in the self-interpretation of the woman’s natural signs of fertility. All methods of NFP in some way help a man and women to get a better picture of their fertility.

Summary Facts on Fertility:

There are a number of biological facts that have been discovered in the past century that are necessary to understand how NFP works. They are as follows:

  • A woman only ovulates one day in each cycle
  • An egg lives only 12 to 24 hours
  • Sperm need good mucus to survive
  • Sperm will live 3-5 days in good mucus
  • Sperm will die within hours or minutes when not in good mucus
  • A man and woman together are only fertile for 6 days


Factors necessary for pregnancy:

  1. Satisfactory ovulation
  2. Healthy and open fallopian tubes
  3. Healthy endometrium for implantation
  4. Healthy cervix with adequate cervical mucus
  5. Healthy and adequate sperm
  6. Mutual and supportive relationship between the husband and wife is helpful.



A man and woman together are only fertile for six days during a women’s menstrual cycle. These 6 days include the day of ovulation and the 5 days before. The timing of these 6 days of fertility (also called the fertile window) can change from cycle to cycle. The figure below illustrates the variability of the fertile window in three consecutive menstrual cycles. The fertile window is indicated by the blue color days, the red color days indicate the days of menstruation (or the woman’s period), and the green days are the days of infertility. The first cycle in Figure 3 is 29 days in length and the fertile window begins on day 10. The second cycle has 25 days and the fertile window begins on day 6 and the third cycle is 34 days in length and the fertile window begins on day 17. The green infertile days before ovulation are absent in the second cycle since ovulation occurred early. In the third cycle the green days before the fertile phase are longer since ovulation occurred later in this cycle. This illustrates that the day of ovulation and the fertile window can vary from cycle to cycle. It also shows that the post -ovulatory phase is the more stable time of the menstrual cycle and that most of the variability occurs before ovulation. The pos- ovulatory phase in the three cycles below ranges from 12-14 days, while the pre-ovulatory phase ranges from 11-23 days.

So, Natural family planning teaches you how to monitor your fertile phase and the variability of the fertile phase from cycle to cycle. Natural family planning utilizes natural markers of fertility to tell you the beginning, peak and end of the fertile phase.