How Do You Predict Ovulation?

Having a good foundation of knowledge about how to predict your ovulation is important, to say the least, when planning a family. However, not everyone will have or make the time to learn about their reproductive hormones and natural ways to predict fertility. That said, we will begin our discussion of the variety of mechanical methods to determine ovulation.

By mechanical, we mean devices that are not part of the human anatomy. This can include computer programs, battery-powered machines, or urine tests. Probably the most popular of these are commonly known as Ovulation Predictor Kits.

Since hitting the over-the-counter market, Ovulation Predictor Kits (OPKs) have become widely-used in the United States. The purpose of these tests is to help a woman know prior to ovulation that her body is at its most fertile. The goal is to detect the luteinizing hormone surge; once this surge is indicated, ovulation should take place in 12 to 48 hours. Accordingly, intercourse which occurs prior to ovulation may result in conception.

OPK’s typically come in a square or rectangular box, have brand-names similar to those of home pregnancy tests (HPTs), and are located on drugstore shelves near the HPT section. Generally more expensive than HPT’s, most OPK’s come with a supply of five testers. This is because a woman may need to use more than one in any given month to detect her LH surge. It is important to read the instructions carefully in order to make the best use of your test–the date that you begin testing is dependent on the typical length of your cycle, so you will need to know that information in advance. Otherwise, you could spend a lot of money testing too early or too late in your cycle!

If you are seeing a medical practitioner for fertility assistance, check with him/her about their own recommendations of OPK brands. Also, they may be able to assist in determining the best day for you to begin testing.

Julie, who as an RN brings a little extra knowledge to her attempts at conception, has successfully used several brands (including store-brands) of OPKs. Like most doctors, hers recommends a preferred name-brand which is one of the more expensive tests.

On the less expensive, store-brand tests that she tried, Julie says they “showed me as not ovulating, even though my periods were exactly 28-29 days. Highly unlikely.” So she tried a different name-brand and found it to be accurate and simple, albeit more expensive. Julie adds that her doctor suggests OPKs be kept in a location away from light and heat, as they are highly sensitive to both. Regarding ovulation detection in general, Julie’s physician believes that using OPKs and tracking cervical mucus changes is the best route to go, particularly if your cycles are regular. For 28-year-old Julie, these methods have thus far helped to produce three total pregnancies and a two-year-old son.

Natural Family Planning

Once you understand the relationship between your hormones, your basal body temperature, and your fertility, you will be able to more easily use the combination of methods referred to as Natural Family Planning, or NFP.

Also referred to as “fertility awareness,” or the “sympto-thermal” method, the goal of NFP is to enhance a woman’s ability to control her own fertility, whether that be for contraceptive or reproductive purposes. Rather than relying on mechanical devices and tests, the methods used in NFP are simply those that are naturally available to any woman–tracking the menstrual cycle and basal body temperature on a calendar, and maintaining awareness of changes in cervical mucus and position.

Noting changes in the cervical mucus and the position of the cervix requires first knowing what those differences are and what they indicate. Generally, during the time that a woman is most fertile, her cervical mucus should undergo chemical and physical changes that enhance delivery of the sperm to the ovum. While most women are at least vaguely aware of the changes in their vaginal discharge monthly, changes in the actual position and structure of the cervix may be foreign to most. This method requires daily attention by the woman to her bodily changes, and again, for several cycles in order to help determine a pattern.

Natural family planning methods can increase your chances at conception, in addition to helping you better know your (or your partner’s) body.

Reproductive Hormones

Understanding how the average woman’s hormones fluctuate with her fertility is the first step; applying that understanding to your own body’s variations is next. While there are only a few days in which conception is possible each month, the process which culminates in ovulation goes on daily. There are a number of hormones involved; a glitch in the amount or delivery of any one may affect fertility. Understanding these hormones can not only increase your chances at fertility, but also help you to feel more in control of your body.

Generally, the hormones which are significant for ovulation are follicle stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone. In the normal series of events, FSH acts first to stimulate ovarian follicle production, which in turn causes a rise in estrogen levels. This rise then stimulates LH to surge–it is this surge that most ovulation predictors are detecting. The surge of LH causes final ovulation; at this time, progesterone is beginning to be secreted by the corpus luteum, and a woman who is ovulating normally can detect a slight increase in basal body temperature.

During all of this hormonal surging, peaking, and subsiding, if all other factors are in sync, the average woman will be able to conceive for approximately 12 to 36 hours beginning at the LH surge. Generally, this is around 2 days immediately prior and up to the day of actual ovulation. When you consider the delicate timing of it all, it can seem a miracle that anyone conceives at all.

As you expand your knowledge about your reproductive hormones, you will find there is more to know. Numerous factors can influence your body’s manufacturing or delivery of these incredibly powerful, but subtle substances.

Your BBT

One of your very first assignments as a person trying to conceive will be to chart your Basal Body Temperature, or BBT. Let’s briefly discuss why this is necessary, how it can affect your efforts at conception, and resources to help you become expert at your charting.

Your basal body temperature is one of the indicators, or informative symptoms, of your own ovulatory functions. As it is the easiest indicator to determine, it is also the first to be suggested by doctors (and required by insurance companies). Even women who have been unable to conceive for years will be asked to chart their BBT when they first approach a medical practitioner for help; while this may seem moot at that time, the practice of charting can be a real learning experience for most women.

A monthly change in your basal body temperature is one of the signals that all may be well with your ovulatory functions. As you may know, as progesterone increases, a slight increase in temp should occur. This change could be as slight as 0.5 to 1.0 degree elevation. Contrary to prior belief, it is now believed that once that temp rise has occurred, a woman may have missed the small window of opportunity to conceive (“Window of Fertility”). This leads to the importance of charting for several cycles in a row, to suggest a pattern.

Most medical practitioners will suggest a woman keep track of her BBT for a minimum of three months. The resulting chart should give you an idea of whether or not you are ovulating on a typically regular basis. It may also give you some idea of when your most fertile days are during the average month.

Specifically, you should use a basal body temperature thermometer, which is available at drugstores for around $5.00 to $15.00 and measures your temp in easily readable tenths of a degree. The first day of your period is considered Day 1 of your cycle; you will place an “x” on the chart for each day of period (not spotting). You may take your temp in any of the usual places (orally, under the arm, or rectally), making sure to do this for the same amount of time (around 5 minutes) each morning immediately after waking and before rising from your bed. It is suggested that you write down the results before going on with your day, to avoid forgetting it later.

Be aware that it is not uncommon for your BBT to be easily affected and influenced by a number of factors: physical activity, alcohol intake, amount of rest, medicines, etc. Therefore, it is important to make note of any and all of these factors when you are charting.

Understanding this very basic fertility-prediction method is a simple, yet crucial step in empowering yourself on your journey. Next, we will take our knowledge one step further and apply it to Natural Family Planning, a combination of methods used to enhance a woman’s control over her reproductive functions.

How to Use an Ovulation Prediction Kit

Ovulation Prediction Kits (OPK’s) are handy tools when trying to conceive. Knowing how to use one can mean the difference between just another month and getting pregnant.

Here’s how:

  1. If you’re seeing a specialist, ask what brand they recommend. If not, ask friends or at online Forums like ours.
  2. Purchase ovulation prediction kit (OPK) based on recommendations and your budget.
  3. Several days prior to using the OPK, read the instructions in the box carefully.
  4. If you are unable to determine from the instructions when you should use the OPK, call your physician immediately.
  5. If you are currently in a treatment cycle (using fertility drugs), follow precisely your physician’s recommendations for days of use.
  6. On the days which you are testing, open a sterile package containing the test wand. You will either urinate on the stick or in a provided cup.
  7. Wait the instructed length of time before reading the results.
  8. If you have difficulty reading the results, call the 800# provided in the instructions, call your physician’s office, or ask others who have used that brand.
  9. Repeat the test with a newly opened sterile package (wand) once a day until you have a positive test.
  10. A positive OPK test means that your luteinizing hormone (LH) surge has been detected and that you will ovulate in anywhere from 12 to 48 hours.
  11. If you are in a treatment cycle (using fertility drugs), notify your physician’s office once you have achieved a positive test.
  12. After a positive test, it is recommend that sexual relations occur before ovulation for maximum conception opportunity.
  13. If you consistently fail to achieve a positive result (after 2 or more cycles), notify your physician.


  1. It is not necessary to wait every other day to engage in intercourse. Daily intercourse will maximize your opportunities.
  2. If you have great difficulty using any particular brand, try another one in the next cycle.

How to Monitor Cervical Mucus to Predict Fertility

Changes in a woman’s cervical mucus are nature’s way of signaling where she is in her cycle of fertility.

Here’s how:

  1. Purchase a small portable calendar or notepad with pen or pencil attached.
  2. Be prepared to check your cervical mucus (CM) consistency several times every day during each cycle.
  3. Using white tissue paper, wipe vaginal opening to obtain CM specimen, or
  4. Insert one clean finger into vagina as far up as the cervix, and then remove finger. CM should be observable on fingertip.
  5. If using tissue, apply a fingertip to collected CM and then pull gently away to test elasticity.
  6. If using finger, test CM elasticity by closing and again opening finger with thumb.
  7. Note the following:
  8. Elasticity of CM: (a) sticky and breaks easily or (b) slippery and stretches like raw egg white.
  9. Appearance of CM: scant amount vs. abundant, white vs. cloudy vs. clear, thick vs. thin.
  10. Note and date your observations regarding elasticity and appearance at the end of each day.
  11. As fertility approaches, CM should gradually change from dry to wet, from sticky to slippery, and from white to transparent.
  12. The most fertile CM is very thin and very slippery, often referred to as EW CM (eggwhite cervical mucus).
  13. If you observe several different types of CM during one day, record the observation with the more fertile characteristics.
  14. The last day on which fertile CM (EW CM) is observed is considered peak fertility day.
  15. Also note days on which sexual intercourse occurs and any bodily discomforts such as cramping, twinges, etc. These are important indicators if you see a specialist.


  1. After you’ve become accustomed to observing your CM, use the following characters to distinguish your notes: P for menstruation or any spotting, D for dry, M for sticky white CM, and F for slippery transparent CM.
  2. Generally, a normally fertile pattern will be 3 to 5 P’s, a few D’s, 2 or more M’s, and 1 to 4 F’s.
  3. This method will only give hindsight information as regards to peak fertility day, so it should be used in conjunction with other ovulation detection methods.

How To Monitor Your Cervix for Fertility

Being aware of simple changes in your uterine cervix can help detect your most fertile times.

Here’s how:

  1. Choose a time of day that is convenient, as you want to do this daily. After your bath is a good time.
  2. Have a pen and paper handy.
  3. Wash and dry hands.
  4. Choose a position that is most comfortable and do not vary from day to day. You can either stand with one foot raised (on toilet) or squat.
  5. Insert index (pointer) finger (or index and middle fingers) into vagina until cervix (opening to the uterus) can be felt. The cervix feels like a smooth indented ball.
  6. Using fingertips, detect any of the following characteristics of the cervix: closed or open, low or raised, tilted or straight, firm or soft, dry or wet. You can discern different characteristics after checking cervix more than once.
  7. Remove fingers from vagina.
  8. Wash and dry hands.
  9. Write down characteristics you observed and the date.
  10. Follow same exact sequence daily throughout your cycle.


  1. Keep nail clipped short on finger used.
  2. If cervix is difficult to reach, push down on abdomen just above pubic bone with other hand to lower uterus.
  3. It may take several cycles to become accurate in your observations.

Chart Your Basal Body Temperature

Keeping track of your monthly cycle via BBT is crucial to beginning infertility treatment or anytime you need to detect your ovulation.

Here’s how:

  1. Purchase a basal body temp (BBT) thermometer.
  2. Obtain a BBT chart from your doctor, or download one from online.
  3. Before bedtime, place BBT chart, a notepad and pen on bedside table or floor.
  4. At bedtime, prepare your thermometer: if mercury, shake down below 98 degrees.
  5. Place thermometer within arm’s reach on bedside table or floor.
  6. Upon waking in the morning, immediately reach for thermometer before doing anything else.
  7. Insert thermometer into mouth, under tongue.
  8. If mercury thermometer, leave in mouth for 5 minutes.
  9. If digital thermometer, leave in mouth until indicator (usually a beep) signals you.
  10. After 5 minutes or the signal sounds, take thermometer out of mouth and look at the reading under good light.
  11. Jot down date and temp reading on notepad.
  12. Scribble a pen dot on the graphline where the date and temperature meet.
  13. After you have more than one temp graphed, connect the dots with a line.


  1. Use the type of thermometer that is easiest for you to read first thing in morning.
  2. Do not do anything else before placing thermometer in your mouth. If possible, don’t move any body part other than your reaching arm.
  3. Jot down temperature reading immediately; do not depend on your memory.

Overview of Predicting Ovulation for Conception

So, you know all there is to know about a woman’s ovulatory cycle, but you’re still trying to conceive? Let’s overview ovulation prediction methods:

Calendar Method

This refers to the standard information that “a woman’s cycle is 28 days in length, therefore she ovulates on Day 14.” Unfortunately, this is a huge generalization. In fact, there is a wide range of normalcy when it comes to menstrual cycles (24 to 35 days), and most women do not have cycles of the exact same length each time.

This means that finding your most fertile time strictly based on the calendar is leaving a lot to chance, which may work out fine if you’re of average or above fertility. If, on the other hand, you’re average or even subfertile, it could result in a tremendous waste of precious time.

Sympto-Thermal Method

This is a combination of methods gaining widespread popularity through books and websites. Sometimes referred to as the “Billings method,” “natural family planning (NFP),” or “fertility awareness methods,” it basically consists of understanding and being aware of the various signs that a woman’s body offers to signal approaching fertility.

Basal Body Temperature (BBT)

BBT simply refers to a baseline reading of your body’s temp, that is, the temp your body typically runs before any physical activity occurs (other than the activity of your organs doing their thing). Keeping track of your BBT, commonly referred to as “tracking” or “charting,” over a period of several cycles can help detect a pattern of fertility.

It is often recommended (or required) by fertility professionals (and insurance companies) that a woman chart her BBT for at least three months before moving forward with any other treatment decisions.

Cervical Mucus (CM) Observation

The quality and quantity of a woman’s cervical mucus (CM) can play a substantial role in fertility. CM refers to what is often called “vaginal discharge,” although some discharge is the result of infections. CM is secreted by the cervix in hopes of assisting sperm on their way to fertilization.

As your body prepares to ovulate, your cervical mucus changes in appearance and texture. Regular observation of CM changes can help detect a pattern of fertility.

Cervical Position Observation

The location and feel-to-the-touch of a woman’s cervix can also act as a fertility signal. As your body prepares for its most fertile time, the cervix should become more open in order to accept sperm into the uterus.

Becoming familiar with cervical changes involves first learning what it feels like during other times of your cycle.

OPK’s, Microscopes, & Other Devices

Ovulation Predictor Kits (OPK)

The most commonly used device for predicting ovulation, OPK’s are usually recommended by fertility specialists (who often also suggest their preferred brand names), particularly during treatment cycles (term referring to any cycle in which conception is attempted using fertility drugs or procedures). As most fertility patients can attest, there are pros and cons to using OPK’s, including cost due to the disposable nature of the kits.

OPK’s work by detecting levels of luteinizing hormones (LH) in your urine. Once LH is detected, it is assumed that ovulation will occur soon, so conception efforts should then commence.

Ferning Microscopes

Not as widely known, ferning scopes have been in use for many years by a smaller population of folks. “Ferning” refers to a microscopic pattern which emerges in both saliva and cervical mucus during specific times of the ovulation cycle. In order to view this pattern, one must slip a small sample of either fluid onto a special microscope. Since the scopes are infinitely re-usable, this can be a more cost-effective means of observing fertility patterns.

Fertility Monitors

Unipath introduced the first round-the-cycle fertility monitor (ClearBlue), and there has been some debate on its benefits. Unipath claims that its major benefit is ClearBlue’s ability to indicate fertility earlier in the cycle, theoretically allowing the woman knowledge of more days in which she is fertile.

The primary differences between the monitor and OPK’s (which are also made by Unipath) are its cost (around US $200), and that one uses it more often in a cycle, rather than only during the few days when one is expecting ovulation.

ClearPlan’s monitor appears to be most beneficial to people of at least average fertility (only women with natural monthly cycles between 21 and 42 days can use it), and there are certain conditions which make use of the monitor ineffective, specifically:

  • menopausal symptoms
  • breast feeding
  • impaired liver or kidney function
  • polycystic ovarian syndrome
  • antibiotics containing tetracyclines (but not oxytetracycline or doxycycline)
  • treatments that affect a woman’s cycle (for example: hormonal contraception, certain fertility treatments and hormone replacement therapy)