Fertility Awareness

by Christiane Northrup, M.D.

Fertility & Birth Control

Much of my work is about helping women get in touch with the natural rhythms of their bodies that connect us not only to our deepest selves, but also to the rhythms of the Earth herself. This is one of the reasons I’ve long been a proponent of fertility awareness and natural birth control. Though you won’t see it in the headlines, natural birth control, particularly what is known as the Ovulation Method, is not only completely safe, it is also remarkably effective at helping couples either avoid or achieve pregnancy when they choose.

Practicing natural birth control allows you to become maximally aware of your fertility and creativity cycles, and to tune into the way in which your body waxes and wanes naturally, like the moon. You know your body intimately and are aware of biologic events such as ovulation, early pregnancy, and impending menopause. To know how to prevent or achieve naturally by being conscious of your fertility is the most profound and empowering knowledge a woman can have.

Ancient Secret Resurfaces

When it comes to birth control, women have a much better option than chemical contraceptives, devices, and sterilization—natural fertility. This approach was first practiced by the Aboriginal tribes. (This may explain why the largest organization, the World Organization of the Ovulation Method Billings [WOOMB] is located in Australia.) It’s a timeless understanding of the female body that was handed down from mother to daughter in ancient times. As was the case in cultures that honored the feminine, women were taught to work consciously with their bodies. And this knowledge was passed on when girls started menstruating. Thankfully, these operating instructions for the female body are still available even though they’ve effectively “been disappeared” from mainstream culture to be replaced by beliefs that the female body is unpredictable and unreliable.

No! It’s not the Rhythm Method

My colleague Joan Morais teaches natural birth control at the University of California Davis Experimental College. When Joan learned about the Ovulation Method (also called the Billings Method), she was looking for a way to tap into the power and wisdom of her body. Joan had taken birth control pills on and off until her late 20s, originally thinking this was the best way to prevent pregnancy. However, she didn’t do well on the pill, experiencing side effects like mild depression and a loss of libido. Most of all, she disliked that the pill made her unable to feel the “waves” of her cycle. When she began practicing the Ovulation Method, she knew she’d found a much better method for both herself and her daughters.

When I talked to Joan she mentioned that many women think natural birth control is the same as the rhythm method. But the Ovulation Method actually has nothing to do with this outmoded approach. With the rhythm method, every woman is thought to have a 28-day cycle, with ovulation taking place on day 14. Women are told to abstain from sex (unless trying to conceive) from about day 12 to 16 of their cycle—the days when they are more fertile. It’s certainly not hard of figure out why this method is so ineffective. It’s based on an “external” device—the calendar—not a woman’s actual biology! It’s a “one size fits all” approach that simply doesn’t reflect the differences among women. For example, many women typically experience longer or shorter cycles as well as cycles that change in duration as they get older. (Even women with regular, 28-day cycles can experience a shorter or longer cycle if they’ve been sick, on medication that month, traveling, or in perimenopause.) This means that the peak fertile period for any given woman can occur earlier or later than the 12 to 16 day range, because everyone’s fertility pattern is unique. Obviously, women having intercourse during their peak time are more likely to get pregnant.

Listen to Your Body

When women and girls are taught about their menstrual cycle, they learn that their ovaries release a fertile egg and that hormonal changes in estrogen and progesterone trigger ovulation and menstruation in the average woman’s cycle. But they are not taught that the buildup and discharge of cervical mucus plays a very key role in fertility.

When a woman’s period ends, mucus forms in the cervix (the mouth of the womb), acting as a barrier that keeps both sperm and germs from entering the womb. Next, a rise in estrogen leading up to ovulation causes the mucus to thin, and it leaves the cervix and exits the body. The mucus is visible at the vulva (the opening to the vagina). (This mucus is infertile mucus.) The rise in estrogen takes place over a few days, ultimately triggering ovulation when the hormone level peaks. Simultaneously, the body produces fertile mucus, a substance that actually enhances sperm’s viability. After ovulation, another mucus plug forms in the cervix, protecting it again from germs and blocking sperm. Approximately 14 days after ovulation, menstruation occurs. And the cycle repeats itself until the final period (menopause).

Fertile cervical mucous is clear and very stretchy. It sometimes comes out in a clump that resembles egg white. When a woman is ovulating, her cervical opening widens and the clear mucous coming from it creates a kind of super highway for sperm. I’ve examined many women during this time, and have often commented that if they want to get pregnant, “Tonight’s the night!” It’s that obvious to me as a doctor.

Spiritual and Holistic Options

When you learn the Ovulation Method, you are taught to recognize the different characteristics of your mucus during different times of the month. Although there are some methods that rely on feeling the cervix to notice any changes, the Ovulation Method relies on external observations only—by feeling the mucous at the opening of the vagina. Using stickers, charts, or universal symbols, you track your fertile and infertile times each month. These supplies are very inexpensive—an entire year’s supply costs less the $10.00.

The first step is to identify your Basic Infertile Pattern, which occurs during the days that follow menstruation before cervical mucous changes are noticed. This varies from woman to woman. Once you know what your infertile mucous feels like, it’s easy to contrast it with the cervical flow associated with peak fertility. Over time, you will learn when you can safely have intercourse without getting pregnant or having to use a back-up method such as a condom, a diaphragm, or enjoying alternatives to intercourse. In a typical month, there’s a 14-day period when you are unable to conceive.

Obviously this is important information to have if you’re trying to prevent pregnancy or conceive. But it also helps you identify if you are bleeding without ovulating or if your periods are slowing down. If you learn this method before having a baby—especially if you are breastfeeding—you’ll also have an idea when your period will resume, along with your fertility! Vaginal secretions that differ from your regular pattern can also indicate an infection or other conditions. One of Joan’s students was able to preempt a serious medical problem because she discussed her observations with her doctor. Initially, he didn’t see anything troublesome, but because this woman really knew her body, her doctor did further testing.

Success Rates

Today, the Ovulation Method is taught and practiced in over 120 countries, and is the preferred method of birth control in China. People of all socio-economic and religious backgrounds practice the Ovulation method, reporting virtually the same success rates regardless of whether they can read and/or live in an underdeveloped country. This speaks volumes about the inherent wisdom of the female body. Fertility awareness techniques (with or without barrier contraceptives during ovulation) can be highly effective birth control techniques. Three major studies show effectiveness rates to avoid pregnancy of 99.1 to 99.9 percent, while actual user rates ranged from 94.8 to 97.3 percent. This effectiveness is about the same as the birth control pill—without any side effects or dangers! Hilgers1  Knowing when you ovulate can enhance your chances of conception considerably. It is generally accepted that the probability of conceiving in one cycle for couples with normal fertility is in the range of 22 to 30 percent. But with fertility focused intercourse, the chances can increase considerably. In one study of couples using fertility-focused intercourse, 71.4 percent of the clients who had a previous pregnancy achieved pregnancy in the first cycle. With those clients who had never had a pregnancy, the rate was 80.9 percent. By the fourth cycle, 100 percent of those who had never been pregnant had conceived. Hilgers2

Remember your fertility is not a disease that requires synthetic drugs 24/7 to “keep it under control.” Nor do your cycles require “regulation” from synthetic hormones. Your body will tell you when it can conceive and when it can’t. But you can enjoy your sexuality 24/7 without risking unwanted pregnancies!

When you tune into the wisdom of your cycle, you’ll see that not only your ovulations, but also your creativity, your libido, and your energy waxes and wanes. (I’ve written about this extensively in Women’s Bodies, Women’s Wisdom.) Your body is truly magical in the way it responds to the same rhythms as the moon, the tides, and the cycles of night and day. And the more you embrace this magic and appreciate it, the healthier you will become. And in so doing, you become a source of health and magic for everyone around you—including your mate.

Learn More — Additional Resources


  1. Hilgers, T.W., 1991. “The Medical Applications of Natural Family Planning: A Contemporary Approach to Women’s Health Care” (Omaha, NE: Pope Paul VI Institute Press); Hilgers, T.W., 1984. “The Statistical Evaluation of Natural Methods of Family Planning,” International Review of Natural Family Planning, vol. 8, no. 3, pp. 226–64; Doud, J., “Use-Effectiveness of the Creighton Model of NFP,” International Review of Natural Family Planning, vol. 9, no. 54 (1985).
  2. Hilgers, T., et al., 1992. “Cumulative Pregnancy Rates in Patients with Apparently Normal Fertility and Fertility-Focused Intercourse,” Journal of Reproductive Medicine, vol. 37, no. 10 (Oct. 1992), pp. 864–66.
Last Updated: February 22, 2007

Christiane Northrup, M.D.

Christiane Northrup, M.D., is a visionary pioneer and a leading authority in the field of women’s health and wellness. Recognizing the unity of body, mind, and spirit, she empowers women to trust their inner wisdom, their connection with Source, and their ability to truly flourish.


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  1. Marilyn
    8 years ago

    Do you have any thoughts on PCOS? My 31-year old daughter has this condition and she and her husband are seeing a fertility specialist for the last few months. They want to get pregnant….harder to do with this condition. She was told to be on a no-carb diet for awhile and then start metformin drug to help her ovulate. With many tests, she was told her tubes and uterus are clear of cysts but her ovaries are loaded with cysts. She plans on starting the drug next week but very concerned with the side effects. Her cycle is all over the place. Any recommendations?

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