Natural Family Planning

Natural family planning is a form of birth control that is based on the timing of sex during a woman's menstrual cycle. Natural family planning used to be called the rhythm method or "safe period." It also is called periodic abstinence or, more recently, fertility awareness. It isn't a single method but a variety of methods.

About Natural Family Planning
Natural family planning can be an effective way to prevent an unwanted pregnancy. It is safe and very low cost.

For this method to work, a woman needs to know her body well, and she and her partner must be willing to follow the method. This method can only work when it is followed correctly at all times.

Natural family planning is not as effective as most other methods of birth control. One in four women who use this method become pregnant.

How Natural Family Planning Works
Each method of natural family planning is designed to help a couple find out which days during a woman's menstrual cycle she is likely to be fertile or able to become pregnant. That way, the couple knows when not to have sex to avoid a pregnancy.

For most women, an egg is released almost two weeks before her next expected menstrual period. The egg remains able to be fertilized for about 24 hours after it is released. Sperm can live in a woman's body for three days or more. The "safe period" includes those days in the menstrual cycle when sex is less likely to lead to pregnancy.

Types of Natural Family Planning
There are five methods of natural family planning:

Basal body temperature method
Ovulation/cervical mucus method
Symptothermal method
Calendar method
Lactational amenorrhea

Whichever method you use, two things are essential: 1) training by a medical professional or a qualified counselor and 2) consistent use of the method.

Basal Body Temperature Method
The temperature method of natural family planning is based on the fact that most women have a slight increase in their normal body temperature just after ovulation. For this method to work, a woman must take her temperature every day. A couple using this method does not have sex from the end of the menstrual period until three days after the increase in temperature.

Ovulation/Cervical Mucus Method
The ovulation method involves changes in how much mucus is produced by the cervix and how it feels. To do this, a woman checks regularly for mucus at the opening of the vagina and looks for such changes.

For instance, for most women the vagina is dry for a time just after menstruation. A sticky mucus then appears. Just before ovulation the mucus becomes wet and slippery. The last day of wetness, called the "peak" day, often occurs at the same time as ovulation.

The safe period is the 10 or 11 days at the end of the cycle and the dry days, if any, that occur just after menstruation.

Although the days of bleeding are thought to be infertile, pregnancy can occur during menstruation.

The ovulation method has advantages over the temperature method in that it does not require the use of a thermometer. However, false readings may be produced by vaginal infection, sexual excitement, and the use of lubricants for sex and certain medications.

Symptothermal Method
The symptothermal method combines the temperature and ovulation methods. In addition to taking the temperature and checking for mucus changes every day, the woman checks for other signs of ovulation:

Abdominal pain or cramps
Spotting
Changes in the position and firmness of the cervix

This method requires that you abstain from sex from the day you first notice signs of fertility (mucus or wet feeling) until the third day after the increase in temperature or the fourth day after the peak day of mucus production.

Calendar Method
The calendar method also is called the rhythm method. To use this method, a woman records every day of her menstrual cycle for 6 months. She then can calculate her fertile period by looking at the calendar.

A menstrual cycle is counted from the first day of menstrual bleeding to the first day of the next menstrual period. A normal menstrual cycle is about 28 days, but can range from 23 days to 35 days. Couples avoid sex during the fertile phase.

The Calendar Method

To calculate the fertile phase:

Subtract 18 from the shortest cycle
(25 days) = 7

Subtract 11 from the longest cycle
(35 days) = 24

Lactational Amenorrhea
Lactational amenorrhea means a woman does not have her period because of a change in hormones caused by breastfeeding.

For this method to work, a woman must be feeding her baby nothing but milk from her breast. The time between feedings should not be longer than four hours during the day or six hours at night.

This method is most effective during the first six months of exclusive breastfeeding. Women using this method have a 2 percent chance of getting pregnant in the first six months after birth. Once vaginal bleeding occurs, the risk of pregnancy is greatly increased.

Finally ... Natural family planning can work only if you and your partner follow the method correctly at all times.

This excerpt from ACOG's Patient Education Pamphlet is provided for your information. It is not medical advice and should not be relied upon as a substitute for visiting your doctor. If you need medical care, have any questions, or wish to receive the full text of this Patient Education Pamphlet, please contact your obstetrician-gynecologist.

To ensure the information is current and accurate, ACOG titles are reviewed every 18 months.