How To Predict Ovulation

What Is Ovulation?

Let’s get down to brass tacks: What happens when you ovulate? You probably learned way back in health class that ovulation is the phase in your menstrual cycle when a mature egg is released from the ovary, setting the stage for fertilization. Every woman is born with millions of immature eggs that wait to be released, normally one at a time, every month. During ovulation the egg travels down the fallopian tube, where it may meet up with a sperm and become fertilized. For most healthy women, ovulation generally happens once a month, a few weeks after menstruation begins.

When Do You Ovulate?

Now that we’ve reviewed what ovulation is, you’re probably wondering when ovulation occurs. You may have heard that ovulation typically happens on day 15 of your menstrual cycle, but it’s not the same for everyone.

If you’re like most women of childbearing age, your menstrual cycle lasts between 28 and 32 days, and ovulation usually hits between days 10 and 19 of that cycle—about 12 to 16 days before your next period. “In healthy women, ovulation occurs 14 days before the onset of your period,” says Donnica L. Moore, MD, president of Sapphire Women’s Health Group in Chester, New Jersey. So if your cycle is 35 days, ovulation will happen on day 21 of that cycle—but if your cycle is 21 days, ovulation will happen on day seven.

The timing of ovulation can vary from cycle to cycle and from woman to woman, adds Shannon M. Clark, MD, associate professor at the University of Texas Medical Branch at Galveston in Galveston, Texas, which is why it’s a good idea to get familiar with your body’s menstrual calendar for at least three months or so, to help you better estimate your own ovulation cycle.

For some women, ovulation doesn’t always take place, or it can be irregular. In general, if you’re pregnant, have gone through menopause or you take birth control pills consistently and on time, you won’t ovulate. Certain diseases or disorders (such as polycystic ovary syndrome or premature ovarian failure, among other conditions) and certain medications (including some antidepressants, anti-nausea medications and chemotherapy) may cause a woman to stop ovulating for periods of time. Also, other lifestyle factors—such as stress or being significantly underweight or overweight (measured by body fat percentage)—may affect menstruation and ovulation.

If you’re dealing with irregular menstrual cycles or ones that are particularly short (fewer than 21 days) or long (more than 35 days), Clark recommends you get evaluated by a physician to rule out any medical conditions that might be causing those irregular cycles. It’s true that tracking ovulation with irregular cycles can be more difficult, but keep in mind that ovulation occurs 14 days before the onset of menstruation, so even with irregular periods, you could still conceive at some point in your cycle.

If you’re planning to breastfeed exclusively (meaning baby won’t get any other source of nutrition), be aware that you likely won’t ovulate during that time. But there are always exceptions, so you can’t depend on breastfeeding as a means of birth control. Once baby is introduced to other foods or the occasional bottle, ovulation is likely to resume. Plan your birth control accordingly, unless you want to give baby a possible surprise—a new brother or sister!

How long does ovulation last?

Once the mature egg is released from the surface of the ovary, it can potentially be fertilized for 24 hours, explains Patricia Pollio, MD, director of OB-GYN at Good Samaritan Hospital in Suffern, New York.

But you don’t have to have sex on the exact day of ovulation in order to get pregnant! In reality, there’s a six-day “fertile window” in your cycle—the five days leading up to ovulation and the day you ovulate, Moore says. Of those six days, you’re most fertile during the two to three days prior to ovulation and the day of ovulation itself.

Beyond 24 hours after ovulation, the egg is no longer viable and you typically can’t get pregnant until your next menstrual cycle. (If you’re not trying to conceive, though, you should still use birth control at all times as a precaution.)

How to Predict Ovulation

Whether you’re trying to conceive or merely want to get to know your body’s signs of ovulation, these indicators, including at-home and OTC tests, can help you learn how to tell if you’re ovulating (or about to).

1. Basal Body Temperature Monitoring

Sometimes referred to as BBT, your basal body temperature is the temperature of your body at rest. At the beginning of your cycle, basal body temperature remains fairly consistent and averages between 97.2 and 97.6 degrees Fahrenheit. As you get closer to ovulation, there’s a slight dip in basal body temperature followed by a sharp increase, typically of about 0.4 to 1.0 degrees, just after ovulation. One way to know if you’re ovulating is to track your basal body temperature over a series of months. Take your temperature with a digital thermometer designed for basal body (you can get one online or at the drugstore) as soon as you wake up, even before you get out of bed, and jot down the reading every morning. Keep in mind that from day to day, your BBT can fluctuate by half a degree or more, so don’t be fooled by a little blip—look for a sustained rise to confirm that you’ve ovulated. After several months the info will give you a good sense of when you usually ovulate so you can plan babymaking accordingly.

Another simple and inexpensive way to track ovulation is to record the days your period begins and ends for several months. If you have normal menstrual cycles—between 25 and 35 days—you’re likely to be ovulating regularly, with ovulation occurring about 14 days before menstruation. Make sure to write down whenever you experience potential signs of ovulation: Typical ovulation symptoms could include cramps, an increase in cervical mucus, breast tenderness, fluid retention, and appetite or mood changes.

3. Ovulation Kit

OTC ovulation predictor kits measure your levels of luteinizing hormone (LH), which can be detected in your urine. These kits work because ovulation typically hits about 10 to 12 hours after LH peaks—on day 14 to 15 of the menstrual cycle if your cycle is 28 days long. Your LH concentration should stay elevated for 14 to 27 hours to allow for full maturation of the egg.

Here’s how the ovulation kit works: Pee on the stick and wait for a line to appear. If the color of the line matches the shade shown on the instructions, ovulation is imminent—within 24 to 48 hours. If it’s too close to call, retest within the next 12 hours. Most kits come with a five-day supply of sticks, to be used in as many days, but check their expiration date: Most of them have a shelf life of only two years. While the majority of ovulation predictor tests can be used any time of day, many of them suggest testing first thing in the morning. For best results, test around the same time each day, and cut back your liquid intake for four hours beforehand, so your pee will be more concentrated and your LH easier to detect.

The real trick to finding success with an ovulation predictor kit is knowing when to start using it. If your cycle is regular, the charting you’ve been doing can help you identify that optimum window. If your cycles are irregular, your best bet is to pay attention to ovulation symptoms. Even if you’ve confirmed that ovulation is happening (through tests or other signs), try to wait to have sex until you notice an increase in cervical mucus, which will heighten the chances of conceiving… to be continued on Wednesday