Ovulation typically occurs once a month. It usually happens halfway through the menstrual cycle. This can vary based on cycle length.

Ovulation is the release of a mature egg from one ovary. This occurs once in every menstrual cycle. After the egg is released, it travels down a fallopian tube to the uterus.

During this part of the menstrual cycle, the person’s reproductive system is ready to receive sperm for fertilization. If fertilization does not take place, the person gets a period.

In this article, we explore the timing and signs of ovulation and how it affects fertility.

The average menstrual cycle is around 28 days. However, every person’s is different, and cycles may vary from 21–35 days.

Ovulation typically occurs halfway through a menstrual cycle. But the actual timing can vary from person to person and month to month. It may happen anywhere from 13–20 days into a cycle.

After ovulating, a person usually gets their period within 14–16 days, unless they are pregnant or have a health condition that affects their period.

The menstrual cycle is the monthly hormonal cycle that the body undergoes as it prepares for the possibility of pregnancy. Each month, ovulation takes place — an ovary releases an egg, which travels down a fallopian tube into the uterus, where it can be fertilized. If it is not, the uterine wall starts to shed its lining, and the body releases this as a menstrual period.

Each new menstrual cycle begins on the first day of a period. Keeping track of these first days can help a person figure out the average length of their cycle and its typical midpoint, when they are likely to ovulate.

Recognizing the signs of ovulation can help a person track their fertility. Five signs that a person may notice include:

Changes in cervical fluid

When ovulating or approaching ovulation, the body produces more estrogen, causing an increase in cervical fluid secretion. When a person is fertile, the cervical fluid in their vagina may be:

  • clear
  • wet
  • more slippery
  • stretchy
  • the consistency of raw egg whites

This type of cervical fluid helps sperm swim into the uterus and fallopian tubes to fertilize the released egg.

To test the cervical fluid’s consistency:

  1. Wash the hands thoroughly with soap and water.
  2. Insert one finger into the vagina near the cervix.
  3. Extract some fluid.
  4. Check it for the above characteristics.

If the fluid is stringy, the person may be close to ovulation. After ovulation, there is less cervical fluid and it thickens.

Changes in basal body temperature

Basal body temperature (BBT) is the temperature of the body at rest. For the most accurate reading, a person should take it as soon as they wake up.

During ovulation, this temperature may slightly increase as the body secretes progesterone, a hormone that helps thicken the uterine lining in preparation for the implantation of an embryo.

Before ovulation, a person’s oral temperature is around 96–98ºF. This may rise to 97–99°F after ovulation. Because the increase is so slight, around 0.4 to 0.8°F, a person needs a special tool, a basal body thermometer, to detect it.

People are at their most fertile 2–3 days before their BBT is at its highest point and 12–24 hours after ovulation.

Because BBT only rises after ovulation, people may prefer other ways of checking their fertility, such as tests that measure levels of luteinizing hormone (LH) in urine.

Also, it is important to note that other factors can raise a person’s BBT, including:

  • consuming alcohol
  • smoking
  • not getting enough sleep
  • having a fever

Increased sexual desire

Some people have a higher sex drive during ovulation. Increased libido tends to coincide with the rise in estrogen and the production of LH that causes the ovaries to release eggs.

Research suggests that the increase in sexual desire may begin 3 days before LH levels peak and last for around 6 days.

Breast tenderness

Breast or nipple soreness or tenderness may be mild to severe during ovulation or when it approaches.

Higher levels of estrogen and LH can cause breast pain in some people just before ovulation. After ovulation, however, the decrease in estrogen and increase in progesterone can also trigger breast and nipple tenderness.

Ovulation pain

Some people feel lower abdominal pain on one side during ovulation. This is known as ovulation pain, or mittelschmerz, and it typically occurs on the ovulating side.

Ovulation pain occurs in more than 40% of people during their menstrual cycles. It often happens as LH levels peak, when the follicle containing the egg to be released is developing but has not yet ruptured. The pain typically stops within 3–12 hours.

Tracking the “fertile window” and ovulation specifically can help a person figure out when they may become pregnant. The window refers to the days in a cycle when pregnancy is possible. Its duration can vary, depending on the length of the cycle.

A person can use an ovulation calculator to determine their fertile window.

People are more likely to conceive if they have sexual intercourse from 5 days before ovulation to 1 day afterward.

Generally, the closer to ovulation, the better the chances of conceiving. Once the ovary releases an egg, the egg dissolves within 24 hours if fertilization does not happen. Sperm can survive in the vagina for 3–5 days, which can influence when fertilization occurs.

For people tracking their fertility at home, urinary LH kits tend to be the most reliable method. Although fertility apps are growing in popularity, they are based on an algorithm and are not always accurate.

Some people avoid having intercourse during their fertile windows to prevent pregnancy, but this method is not reliable — research suggests that pregnancy occurs in 19% of cases.

Anyone who wants to prevent pregnancy should discuss other approaches with a healthcare professional.

Sometimes, the signs of ovulation can instead stem from a health problem. For example, endometriosis can mimic ovulation pain. If any issues consistently arise halfway through a cycle, it might be a good idea to consult a doctor.

If pain does result from ovulation, a doctor can describe ways to ease it.

People should receive prompt medical care if they experience:

  • intense pain that lasts for several days
  • pain that interferes with daily activities
  • vaginal bleeding
  • a fever

Ovulation usually occurs halfway through a menstrual cycle. Some signs of ovulation include:

  • pain in the lower abdomen, possibly on one side
  • breast tenderness
  • cervical fluid that is extra stringy or slippery
  • a higher sex drive
  • a rise in BBT

If intense, lasting pain or vaginal bleeding occurs during ovulation, a person should receive medical attention as soon as possible.