What is Natural Family Planning (NFP)?

Ever wonder what natural family planning really means? And why some people use it? In this article, we explain why and how to use NFP to achieve—or avoid—pregnancy.

By Halle Tecco, MBA, MPH

Natural family planning (also called “fertility awareness methods”) is a method of family planning that does not use hormonal contraception, long-acting reversible contraception (like IUDs), or condoms. Some couples use NFP for getting pregnant, while others use it to prevent pregnancy. Natural family planning involves identifying the signs and symptoms of fertility during your menstrual cycle, so you can time intercourse in order to achieve or avoid pregnancy. There are many variations and methods to choose from, and we will go over those in this guide. 

How does natural family planning (NFP) work?

Identifying your fertile window is the core tenet of most NFP methods. This is done through:

• Charting your cycle in a calendar or using an online ovulation calculator
• Predicting ovulation with ovulation predictor kits, often referred to as OPKs
• Tracking basal body temperature
• Tracking cervical mucus
• Tracking fertility symptoms (e.g., breast tenderness ovulatory pain)
• A combination of the methods above 

Some people choose to track on their own on paper or through an app. Others choose to take a course or follow an instructor. For most methods, they say it takes three to six menstrual cycles to truly learn the method. 

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So, what’s a fertile window anyway?

A woman’s “fertile window” is the five day period of time leading up to ovulation, plus the day of ovulation itself (so, six days total). Since sperm can live inside a woman’s body for up to five days, having sex at the beginning of your fertile window before an egg is released can still lead to pregnancy. 

Some women experience noticeable signs of this fertile window, such as abdominal pain (called mittelschmerz, German for “middle pain”), light spotting, breast tenderness, bloating, and an increased sex drive. Cervical mucus (aka vaginal discharge) also changes during this time. The cervical mucus produced right before and during ovulation is translucent, stretchy, and more copious. It has a similar consistency and appearance to egg whites. This is called fertile-quality cervical mucus because it’s ideal for helping sperm move along their journey into the uterus and fallopian tubes.

Read Dr. Naz’s article, How To Track Ovulation.

Does natural family planning work? Is it effective?

For most people, the effectiveness of natural family planning is 76 percent. However, perfect use of these methods can be at least 95 percent effective. The effectiveness depends on your diligence to track and record your fertility biomarkers properly. To put that into perspective, birth control pills are 91% effective and an Intrauterine Device (IUD) is 99%+ effective.

There are many natural family planning methods

• Billings Ovulation Method uses cervical mucus tracking to track your fertile window.
• The Boston Cross Check method is based on the observation and interpretation of changes in cervical mucus and basal body temperature and includes hormonal monitoring.
• The Creighton Model (CrM) was developed by the Catholic Church and uses the technique of cervical mucus tracking. It is a modification of the Billings Ovulation Method. A meta-analysis of five studies found the effectiveness rates for avoiding pregnancy were 99.5 and 96.8 percent.
• Lactational Amenorrhea Method is an option available during the first six months following childbirth. When you exclusively breastfeed, your body oftentimes naturally stops ovulating, meaning you can’t get pregnant. Lactational amenorrhea is 92-100 percent effective in preventing pregnancy during the first six months postpartum in women who exclusively breastfeed their infants.
• The Marquette Model was developed at Marquette University. Followers identify their fertile window by using an electronic hormonal fertility monitor and their cervical mucus. 
• Standard Days Method or the Rhythm method is a birth control method using calendar tracking and only available to women with very regular periods. The Standard Days method says not to have sex on days 8-19 of your cycle to avoid pregnancy. 
• The Sympto-Thermal Method (STM) is based on three key signs of fertility: cervical mucus, basal body temperature, and changes in the cervix. 
• The Twoday Method encourages use of a simple card to track cervical mucus twice a day. If you notice secretions of any type, color, or consistency either “today” or “yesterday,” you would consider yourself fertile.

Fertility tracking using ovulation predictor kits (OPKs)

You can pinpoint your fertile window using ovulation tests (aka ovulation predictor kits or OPKs). The process is similar to taking a pregnancy test because the test detects the presence of hormones in urine. Ovulation tests identify the LH surge (the surge of hormone that triggers ovulation) by detecting the presence of an abundance of LH in urine. Once the LH surge has occurred, ovulation usually takes place within 12 to 36 hours. 

A positive ovulation test means you are in your “LH surge” and that it’s an time to have or avoid sex, depending on your goals. Keep in mind, you’ll want to know your pattern of ovulation (what day in your cycle you get a positive test) for future months in order to make use of the full fertile window. 

🌟 Shop Ovulation Predictor Kits

Who can use natural family planning?

According to the NHS, most women can use natural family planning. However, certain situations can affect the signs and symptoms of fertility, making it a less effective method. This includes:

• Having an irregular period
• Having a condition affecting your fertility signs, such as a sexually transmitted infection (STI) or pelvic inflammatory disease
• Taking a medication that disrupts production of cervical mucus
• Recently stopping hormonal contraception
• Having a recent miscarriage or abortion
• Being a heavy drinker

Ask your doctor about natural family planning

Family planning, whether to achieve or avoid pregnancy, is a great discussion to have with your OBGYN. Your doctor can tell you if there are any conditions that may prevent you from using natural family planning or if any medications you’re on will disrupt the symptoms you want to track. Good luck!