Natural Family Planning


What is natural family planning?

Natural family planning is a method used to help a couple determine when sexual intercourse can and cannot result in pregnancy. During the menstrual cycle, a number of changes occur in a woman's body. By keeping track of these changes, couples can plan when to have intercourse and when to avoid intercourse, depending on whether they are trying to achieve or avoid pregnancy.

During each menstrual cycle, one of a woman's ovaries releases an egg. This process is called ovulation. The egg moves toward the uterus through the fallopian tubes, where fertilization may take place. An unfertilized egg may live for up to 12 hours. The egg will be shed later during the menstrual period if it isn't fertilized. A woman is most likely to become pregnant if sexual intercourse takes place just before or just after ovulation.

How does natural family planning work?

Two methods of natural family planning are currently taught. The first is the mucus or ovulation method. In this method, the days just before and just after ovulation are determined by checking the woman's cervical mucus. When a woman is most likely to become pregnant, the cervical mucus is stretchy, clear and slick. The mucus during this time looks and feels much like an uncooked egg white.

The second method is called the symptothermal method. With this method, the woman takes her temperature each day with a basal body temperature thermometer and writes it down on a chart. At the time of ovulation, a woman's temperature will rise slightly (about .9°F). The woman also checks the consistency of her cervical mucus like she does with the mucus method. She may also notice other changes, such as pain in the area of the ovaries, bloating, low backache and breast tenderness.

In both methods, couples use a chart to keep track of the changes in the woman's body.

How effective are these methods in helping a couple avoid pregnancy?

These methods can help a couple avoid pregnancy if the couple receives training from a specialized instructor and if they carefully follow all of the instructions provided. (Ask your doctor how to find an instructor who is specially trained in teaching natural family planning.) Both methods can be 90% to 98% effective (2 to 10 pregnancies per 100 couples) when they are practiced correctly. However, if a couple doesn't follow the instructions completely, these methods will be much less effective. In practice, these methods may not be as reliable as other forms of birth control.

Can natural family planning help a couple achieve pregnancy?

Yes. As many as 2 out of 3 couples who don't have fertility problems become pregnant if they have sexual intercourse on the days that the cervical mucus is clearest and most stretchable.

What about the rhythm method?

The rhythm method is based on calendar calculations of previous menstrual cycles. This method doesn't allow for normal changes in the menstrual cycle, which are common. The rhythm method isn't as reliable as the mucus method or the symptothermal method and is generally not recommended. Women who have no variation in the length of their menstrual cycles can use the rhythm method to know when they are ovulating (usually 14 days before the start of their period).

What about women who have irregular cycles or who are breastfeeding?

It is common for a women to have menstrual cycles that are irregular (either longer or shorter than 28 days). A woman who has irregular menstrual cycles may still be able to tell when she is ovulating by watching for the changes in her body.

Special instructions have been developed for mothers who are breastfeeding their babies. Ask your doctor for these instructions if you are breastfeeding.

Written by editorial staff

Reviewed/Updated: 07/10
Created: 09/00