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Natural Family Planning

What is natural family planning?

Natural family planning is a term used for methods of birth control that do not involve the use of any drugs or devices. It is also called the rhythm method, fertility awareness, or periodic abstinence. If you do not want to get pregnant, you should not have sex during the fertile days (days you are more likely to get pregnant) of your menstrual cycle.

When is a woman fertile?

An average menstrual cycle lasts approximately 26 to 32 days. Normally during each menstrual cycle an egg is released from one of your ovaries. The release of an egg is called ovulation. The egg travels through a fallopian tube to the uterus. The egg can be fertilized by sperm as it travels to the uterus. If the egg is not fertilized after it leaves the ovary, it is absorbed by the body, or your body gets rid of it during the monthly period.

Sperm can live inside your body for 3 days after you have sex. This means that you can get pregnant up to 3 days after you have sex if you ovulate during that time.

How do I use natural family planning?

Natural family planning birth control methods are based on calculating when your fertile days will occur. You should not have sex during your fertile days if you do not want to get pregnant.

There are 6 types of natural family planning methods:

  • basal body temperature
  • cervical mucus or ovulation
  • symptothermal
  • calendar
  • standard days
  • lactational amenorrhea (breast-feeding)

Other changes, such as pain in the area of the ovaries, low backache, breast tenderness, and bloating also may be used to help you know which days you are fertile.

The length of the menstrual cycle varies from woman to woman. It can also vary month to month. Natural family planning methods depend on accurately recording information about your menstrual cycle and calculating safe days for sex. These methods require a strong commitment from both partners. Usually women between 20 and 40 years-old have more regular menstrual cycles. For this reason, natural family planning is more effective for women in this age group.

If you choose to use natural family planning birth control, you should use another method of birth control that does not contain hormones until you and your partner are aware of your most likely ovulation days. Barriers (such as diaphragms or condoms) and spermicides will not affect your natural family planning measurements. You and your partner should be comfortable with the natural family planning method that you choose before using it as your only method of birth control.

How do I use the basal body temperature method?

Basal body temperature (BBT) is your temperature as soon as you wake up from sleep in the morning. Your BBT rises slightly with ovulation. So by recording this temperature daily for several months you'll be able to predict your most fertile days. You will need to measure your temperature with a special, basal body thermometer right after you wake up--before you get out of bed, eat, drink, smoke, or have sex. This type of thermometer can detect small changes in temperature. You can buy one at a drug store. Your temperature will rise about 0.5 to 1F (0.5C) just after you ovulate. It will stay at this higher level until your next menstrual period starts. If you do not want to get pregnant, you should not have sex from the time your menstrual period ends until 3 days after your temperature rises. Write down your BBT every day on a calendar.

When you use this method of birth control it is important to remember that illness and any drugs, including alcohol, can raise your body temperature.

How do I use the cervical mucus or ovulation method?

Cervical mucus is a jellylike vaginal discharge that comes from the cervix. The cervix is the opening of the uterus into the vagina. The cervical mucus is thick and sticky during most days of the menstrual cycle. It usually becomes clear, thin, and watery (like uncooked egg white) about 4 days before ovulation.

You can check the cervical mucus with your finger or a piece of toilet paper. When the mucus is clear, thin, and watery, these days are called wet days. If you do not want to get pregnant, you should not have sex from the time the wet mucus appears until 4 days after the mucus becomes thick, sticky, and smaller in amount. Be careful that you don't confuse wet day mucus with semen that leaves your vagina after intercourse.

You may also buy ovulation kits, which can show you exactly when you ovulate.

How do I use the symptothermal method?

The symptothermal method uses a combination of the basal body temperature and cervical mucus methods to determine the most likely time you can become pregnant. You will need to check your temperature and cervical mucus every morning.

How do I use the calendar method?

The calendar method is also called menstrual charting. You must keep track of your menstrual cycles for 8 cycles. The time that you are most likely to become pregnant is measured by subtracting 18 days from the number of days of your shortest cycle, and subtracting 11 days from the number of days of your longest cycle. For example, if the shortest number of days in your menstrual cycle is 28 days (28 - 18 = 10), and the longest number of days in your menstrual cycle is 32 days (32 - 11 = 21), then the most likely time for you to become pregnant is between days 10 and 21 of your menstrual cycle. If you do not want to get pregnant, you should not have sex during this time.

How do I use the standard days method?

This method can be up to 95% effective in the best-case situation. On a calendar, mark the day when your period first begins as Day 1 and circle it. Then mark the same day of the week, 1 week later, as Day 8 and circle it. Count forward to Day 19 and circle it. Draw a solid line through days 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 19. Days 8 through day 19 are days of increased fertility and an increased chance of conception. For these 12 days (days 8 through 19), do not have sexual intercourse if you want to avoid getting pregnant.

All other days within each cycle have a low risk of conception. You do not need to abstain from sexual intercourse on days 1 through 7, nor on days 20 through the end of each cycle. A cycle ends when your next period starts. Mark the day your next period starts as Day 1 of the next cycle. Then go back to the previous cycle on the calendar and count the total number of days in the previous cycle. Put a square around the total number of days for that cycle and do the same thing for each following cycle. If a cycle was 30 days long, the last day will be marked 30. Keep these calendar pages, so that you have a record of how long each cycle was.

Importantly, only 1 cycle per year can be less than 26 days or more than 32 days. If more than 1 cycle per year was shorter than 26 days or longer than 32 days, use a different method of natural family planning.

How do I use the lactational amenorrhea method?

Lactational amenorrhea means that you do not have a menstrual period or ovulate while you are breastfeeding. You may only use this method if you are breastfeeding, and your infant is not taking any other foods or formula. You must breastfeed at least 8 to 10 times per day, with no more than 6 hours between feedings if you do not want to get pregnant. You should not use this method of birth control if you are not breastfeeding this often, if your infant is taking other foods or formula, or if you begin to have menstrual bleeding.

How effective is natural family planning?

Natural family planning methods of birth control can be 91 to 98% effective (2 to 3 pregnancies per 100 couples) when they are used correctly all of the time. However, this is hard for most couples to do. If you do not follow the instructions completely, or if you have irregular menstrual periods, these methods are much less effective. They are less reliable than some of the other forms of birth control. Women who should not get pregnant for health reasons should not use natural family planning as a method of birth control.

What are the benefits?

The advantages of natural family planning are:

  • You can have some control over when you have children without using drugs or devices.
  • You can enjoy sex without the interruption or discomfort of barrier methods of birth control, such as condoms or diaphragms.
  • You can avoid the health risks of some methods such as birth control pills and the IUD.
  • It costs very little.

What are the disadvantages?

Natural family planning has several disadvantages, which include:

  • If it is not practiced carefully, the failure rate can be as high as 25%. This means 2 to 3 of every 10 women get pregnant during 1 year of use.
  • There are days every month when you should not have sex.
  • It requires time, energy, commitment, and careful record-keeping.
  • It does not protect against sexually transmitted diseases, including AIDS.

How can I learn more about natural family planning?

Classes are available for couples who choose to use natural family planning methods. This form of birth control should not be attempted until both partners have had the class and are comfortable with using this method.

For more information on family planning, contact your healthcare provider or the following organizations:

  • National Women's Health Information Center sponsored by the US Department of Health and Human Services at or call (800) 994-WOMAN
  • Institute for Reproductive Health sponsored by the US Agency for International Development at: or call (202) 687-1392.
Developed by Phyllis G. Cooper, RN, MN, and RelayHealth.
Published by RelayHealth.
Last modified: 2010-01-28
Last reviewed: 2009-01-24
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
2010 RelayHealth and/or its affiliates. All Rights Reserved.
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