Factors that influence the effectiveness of natural family planning in avoiding pregnancy

Natural family planning is most effective:

Natural family planning as a method of fertility regulation is extremely effective under the following conditions:

  • The couple are well motivated.
  • There is strict adherence to the rules.
  • The fertility indicators are recorded daily and accurately.
  • There is accurate interpretation of the chart.
  • Good teaching by the natural family planning teacher.


The effectiveness of natural family planning depends decisively on how strongly motivated the couple are in avoiding pregnancy and on whether the couple have discussed and agreed their family planning intention and are indeed as one in this intention.

Adhering to the rules of the NFP Method used:

The effectiveness of natural family planning largely depends on the behaviour of the couple. Most unintended pregnancies happen because the couple did not adhere to the rules of the method and knowingly had sexual intercourse in the fertile time. Many take a one-off risk knowing that the possibility of pregnancy is not so high at the beginning of the fertile phase believing ‘nothing will happen this time’.1

The probability of pregnancy increases when sexual intercourse occurs closer to ovulation. After ovulation the probability of pregnancy recedes quickly. In the post ovulatory phase when the couple adhere to the rules the risk of pregnancy is nil as the ovum is dead and another ovulation will not occur in that cycle.

Good teaching by the NFP teacher:

It is especially important that the fertile period is correctly identified, hence the necessity for those couples who are learning natural family planning to receive correct training from a qualified natural family planning teacher. Personal instruction of the client will help the woman to get a proper understanding of the subject and will therefore promote compliance and maximum effectiveness.


1 Frank-Herrmann et al; ‘Effectiveness and acceptability of the symptothermal method of natural family planning in Germany; Am J Obstet Gynecol 1991; 165; 2052-4

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