What is ovulation?

Ovulation is a part of your menstrual cycle. It occurs when an egg is released from your ovary.

When the egg is released, it may or may not be fertilized by sperm. If fertilized, the egg may travel to the uterus and implant to develop into a pregnancy. If left unfertilized, the egg disintegrates and the uterine lining is shed during your period.

Understanding how ovulation happens and when it takes place can help you achieve or prevent pregnancy. It can also help you diagnose certain medical conditions.

Where does ovulation fit into your overall menstrual cycle?

Your menstrual cycle resets the day that your menstrual flow begins. This is the start of the follicular phase, where the egg matures and is later released during ovulation.

During the follicular phase, your body will release follicle-stimulating hormone (FSH) that helps the egg inside your ovary mature and prepare for release.

Once the egg is mature, your body releases a surge of luteinizing hormone (LH), triggering the egg’s release. Ovulation usually happens around day 14, in the 28 to 36 hours after the LH surge.

After ovulation comes the luteal phase. If pregnancy occurs during this phase, hormones will keep the lining from shedding. Otherwise, bleeding will start around day 28 of the cycle, beginning the next cycle.

In short: Ovulation generally occurs in the middle of the menstrual cycle.

The 6 days leading up to and including ovulation make up what’s called the “fertile window.” This is the period of time when sexual intercourse may lead to pregnancy.

The sperm may wait around for several days in the fallopian tubes after sex, ready to fertilize the egg once it’s finally released. Once the egg is in the fallopian tubes, it lives for around 24 hours before it can no longer be fertilized, thus ending the fertile window.

Impending ovulation can cause more vaginal discharge. This discharge is often clear and stretchy. Sometimes it may resemble raw egg whites. After ovulation, your discharge may decrease in volume and appear thicker or cloudier.

Ovulation may also cause:

  • light bleeding or spotting
  • breast tenderness
  • increased sexual drive
  • ovary pain, characterized by discomfort or pain on one side of the abdomen

Not everyone experiences symptoms with ovulation, so these signs are considered secondary in tracking your fertility.

It’s fairly common to experience pain during ovulation. Up to 40 percent of people who ovulate feel some discomfort around the midpoint of their menstrual cycle.

This condition is also known as mittelschmerz, which means “middle pain“ in German.

The pain usually occurs each month. You’ll feel it on either the left or right side of the lower abdomen, depending on which ovary is releasing an egg that month.

The pain can range from mild to severe. It might feel achy, or sharp like a cramp.

If the pain is severe, talk with a doctor. There may be options to reduce your discomfort. A doctor can also determine if further testing or treatment is necessary.

In rare cases, pain during ovulation is a sign of an underlying condition, such as:

There are several ways to figure out when ovulation happens:

  • Menstrual cycle. Ovulation typically happens around day 14 of a 28-day menstrual cycle, counting from the first day of your period. But normal cycles can be as short as 21 days in adults, or as long as 35 days. You’ll want to track your cycle over multiple months to learn its length. You’re likely to ovulate around the middle date of your cycle, give or take a few days.
  • Body temperature. Your temperature rises slightly for a few days after ovulation takes place, by about 0.5 to 1.3°F (0.3 to 0.7°C). You may be able to detect the change by taking your temperature every morning. Read more about Basal Body Temperature (BBT) charting.
  • Vaginal discharge. There’s likely more of it around the time of ovulation. It’s usually more clear and more slippery.
  • Using at-home trackers. Over-the-counter (OTC) options include ovulation predictor kits and fertility monitors.

Using several of these methods together is more likely to give you an accurate answer.

For example, body temperature charting is influenced by more than ovulation alone. It’s also affected by factors like illness or alcohol use.

If your period is irregular or absent, this may be a sign that you are not ovulating each month.

While the most accurate way to confirm ovulation is with an ultrasound or hormonal blood tests ordered by your doctor, you have options when it comes to tracking ovulation at home.

  • Ovulation predictor kits (OPKs). These are generally available OTC at your corner drugstore. They detect the presence of LH in your urine, which usually means you will ovulate soon.
  • Fertility monitors. These are also available OTC. They track two hormones — estrogen and LH — to help identify your fertile window. Fertility monitors can be pricier than options that track LH only. Some monitors claim to detect 4 or more fertile days each month with 99 percent accuracy.

Always follow the manufacturer’s instructions to ensure you’re making the best use of at-home trackers. Talk with a doctor or pharmacist to determine which of these tools is right for you.

If you track ovulation from one month to the next, you may notice that you’re either not ovulating regularly or, in some cases, not ovulating at all. This is a reason to speak with a doctor.

Things like stress or diet may affect the exact day of ovulation from month to month. There are also medical conditions, like polycystic ovary syndrome (PCOS) or thyroid disorders, that may make ovulation irregular or stop completely.

These conditions may cause other symptoms related to changes in hormone levels, including:

  • increased growth of facial or body hair
  • acne
  • infertility, in some cases

You only need to have sex once during your fertile window to achieve pregnancy. People who are actively trying to conceive may increase their chances by having sex every day or every other day during the fertile window.

For those using intrauterine insemination (IUI) to try to conceive, IUI is also conducted during the fertile window.

The best time to get pregnant is in the 2 days leading up to ovulation and the day of ovulation itself.

If you want to prevent pregnancy, it’s important to use birth control. This is especially important during your fertile window.

Although barrier methods like condoms are better than no protection at all, you may have greater peace of mind when using a more effective method. Options with very high efficacy include the contraceptive implant and IUDs. Birth control pills are also more effective than barrier methods.

Keep in mind that in a year of “typical” use, 12 to 24 out of 100 people will get pregnant while using fertility awareness methods, like BBT charting, to prevent pregnancy.

Your doctor can walk you through your options and help you find the best approach.

Can you ovulate more than once in a given cycle?

Maybe, but it’s not clear whether this would have any additional effect on fertility. One study from 2003 suggested that some people have the potential to ovulate two or three times in a given menstrual cycle. But other researchers disagreed with the conclusions, emphasizing that only one fertile ovulation happens per cycle.

It’s possible to release multiple eggs during one ovulation. Releasing multiple eggs can happen spontaneously, or as part of treatments for infertility. If more than one egg is fertilized, this situation may result in fraternal multiples, like twins. Approximately 2 out of every 3 sets of twins are fraternal (nonidentical) twins.

Is ovulation the only time you can become pregnant?

No. While the egg can only be fertilized in the 12 to 24 hours after it’s released, sperm can live in the reproductive tract under ideal conditions for about 5 days. So, if you have sex in the days leading up to ovulation or on the day of ovulation itself, you may become pregnant.

If you are not trying to get pregnant, using contraception is your safest option, at all times of your cycle.

If you’re looking to get pregnant in the near future, consider making a preconception appointment with a doctor. They can answer any questions you may have about ovulation and tracking, as well as advise you on how to time intercourse to increase your chances.

They can also identify any conditions that may be causing irregular ovulation or other unusual symptoms.

If you aren’t trying to conceive, a doctor can help you choose the right method of contraception for you.