What is Natural Family Planning (NFP)

Natural Family Planning is a type of birth control (contraception) in which no form of contraceptive medicine or device is used. The NFP method relies on knowing which days of the month a woman’s ovary is producing an egg (ovulation).

Ovulation is the time in the menstrual cycle when a woman is most fertile and, therefore, most likely to become pregnant. To lower the chance of pregnancy, sex is avoided during ovulation.

NFP is a safe method of birth control and can prevent pregnancy if it is done correctly. However, NFP does not provide protection from sexually transmitted diseases. NFP can also be used as a method of getting pregnant, by deciding to have sex during ovulation.

How does the NFP method work?

NFP works by making both sexual partners aware of how the woman’s body functions during her menstrual cycle.

• Usually, a woman has a menstrual period every 28–30 days. However, there can be 23–35 days between each menstrual period. This varies for each woman. A woman with a 28-day menstrual cycle has about 6 days a month when she is most likely to get pregnant.
• Ovulation happens 12–14 days before the start of the next menstrual period. There are different methods that are used to determine when ovulation starts.
• An egg is fertile for 24 hours after it is released from the ovary. Sperm can live for 3 days or more.

What NFP methods can be used to prevent pregnancy?

The basal body temperature method

During ovulation, there is often a slight increase in body temperature. To use this method:

• Take your temperature every morning before getting out of bed. Write the temperature on a chart.
• Do not have sex from the day the menstrual periods starts until 3 days after the increase in temperature.

Note that body temperature may increase as a result of various factors, including fever, restless sleep, and working schedules.

The cervical mucus method

Right before ovulation, mucus from the lower part of the uterus (cervix) changes from dry and sticky to wet and slippery. To use this method:

• Check the mucus every day to look for these changes. Ovulation happens on the last day of wet, slippery mucus.
• Do not have sex starting when you first see wet, slippery mucus and until 4 days after it stops or returns to its normal consistency.
• With this method, it is safe to have sex:
  • After the 4 days have passed, and until 10 days after the menstrual period starts.
  • On days when mucus is dry.

Note that cervical mucus can increase or change consistency due to reasons other than ovulation, such as infection, lubricants, some medicines, and sexual arousal.

Other variations of the cervical mucus method include the TwoDay method, Billings ovulation method, and the Creighton model.

The symptothermal method

This method combines the basal body temperature and the cervical mucus methods.

The calendar method

This method involves tracking menstrual cycles to determine when ovulation occurs. This method is helpful when the menstrual cycle varies in length. To use this method:

• For 6 months, record when menstrual periods start and end and the length of each menstrual cycle. The length of a menstrual cycle is from day 1 of the present menstrual period to day 1 of the next menstrual period.
• Use this information to determine when you will likely ovulate. Avoid sex during that time. You may need help from your health care provider to determine which days you are most likely to get pregnant.
  • Ovulation usually happens 12–14 days before the start of the next menstrual period.
  • Light vaginal bleeding (spotting) or abdominal cramps during the middle of a menstrual cycle may be signs of ovulation. However, not all women have these symptoms.

The standard days method

This method is based on studies of women’s hormone levels throughout normal menstrual cycles. Based on these studies, a standard rule was developed to predict when women are most fertile during their menstrual cycle. According to the rule, if your cycle is 26–32 days long, you are most fertile between days 8 and 19. To prevent pregnancy, you should avoid having sex during this time, or use a barrier method of birth control. This method works best if your cycle is regularly between 26–32 days long.

When should I not use the NFP method?

You should not use NFP if:

• You have very irregular menstrual periods or you sometimes skip a menstrual period.
• You have abnormal vaginal bleeding.
• You recently had a baby or are breastfeeding.
• You have a vaginal or cervical infection.
• You take medicines that can affect vaginal mucus or body temperature. These medicines include antibiotics, thyroid medicines, and antihistamines that are found in some cold and allergy medicines.
• You absolutely do not want to become pregnant at the current time. Other methods of contraception are more effective at preventing pregnancy than NFP.
• You are concerned about sexually transmitted diseases.

Summary

• Natural Family Planning methods help women and their partners to understand how to avoid pregnancy without using medicines or other methods.
• A woman learns to recognize her most fertile days. A woman with a 28 day menstrual cycle has about 6 days per month when she can get pregnant.