Late or delayed ovulation is ovulation that occurs after day 21 of your menstrual cycle. Ovulation is the release of a mature egg from an ovary. It’s triggered by the monthly rise and fall of certain hormones, namely:

  • estrogen
  • progesterone
  • luteinizing hormone
  • follicle-stimulating hormone

Ovulation generally occurs midway through your menstrual cycle. The average cycle is about 28 days long, meaning ovulation generally occurs around day 14 of your cycle. There can be a great deal of variation, however.

Read on to learn more about late ovulation, how it affects fertility, and how its treated.

The menstrual cycle is divided into three phases:

  • the follicular phase, in which the ovarian follicles develop and an egg matures in anticipation of its release
  • ovulation
  • the luteal phase, in which the follicle closes and hormones are released to trigger shedding of the uterine lining, unless pregnancy has occurred

While the luteal phase remains pretty constant, lasting about 14 days after ovulation (the release of an egg is just a few hours long), the follicular phase can vary in length from 10 to 16 days. If the follicular phase is prolonged, ovulation will be late or even absent.

Late ovulation is usually caused by hormonal imbalances, which may be temporary or long-term, depending on the cause. Some things that can lead to a hormonal imbalance include:

Stress

Extreme stress, either physical or emotional, can have a negative impact in a variety of ways, including hormonally. In one study, researchers noted that the rate of menstrual disorders more than doubled in a group of Chinese women following an 8.0 earthquake.

Thyroid disease

Your thyroid impacts the pituitary gland. The pituitary gland is a region of the brain responsible for some of the hormones necessary for ovulation. Having either an underactive or an overactive thyroid can cause problems with ovulation.

Polycystic ovary syndrome (PCOS)

PCOS is a condition in which testosterone is overproduced. Too much testosterone prevents the ovaries from releasing an egg. Irregular menstruation is a common symptom of PCOS.

PCOS affects 1 out of every 10 women.

Breastfeeding

Prolactin, the hormone necessary for the production of breast milk, suppresses ovulation and menstruation. If you breastfeed exclusively, your period may stop while you’re nursing.

However, breastfeeding shouldn’t be used as a form of birth control. Ovulation can return two weeks before menstruation.

Medications

Certain medications and drugs can inhibit ovulation, including:

  • long-term use of nonsteroidal anti-inflammatories (such as Advil or Motrin)
  • some antipsychotic medications
  • marijuana
  • cocaine

In one study, researchers looked at the effect of the drug meloxicam, which is used to treat arthritis, on ovulation. Study participants experienced a five-day delay in follicular rupture and the subsequent release of an egg compared with those taking a placebo.

Ovulation occurs about midway through your cycle. So, if you normally have a 28-day cycle, ovulation should occur about day 14, although it’s common for it to occur a few days before or after the midpoint of your cycle. If you have delayed or irregular ovulation, however, relying on the calendar won’t always be an effective way to determine when you’re ovulating.

You may be able to use some physical cues to identify ovulation, including:

  • An increase in cervical mucus. If your vaginal secretion is clear, stretchy, and resembles egg whites, you may be ovulating or about to ovulate. This mucus will appear right around ovulation to help sperm meet the released egg.
  • An increase in basal body temperature. Basal body temperature is your temperature when you’re at rest. A slight rise in your temperature can indicate ovulation. To track your basal body temperature, take your temperature before you get out of bed in the morning and document it so you can easily identify changes in body temperature.
  • Side or lower abdominal pain. Also called mittelschmerz, you may feel one-sided pain and even experience some breakthrough bleeding as the egg gets released from the ovary.

Ovulation predictor kits

Ovulation predictor kits can also track ovulation. These kits contain sticks that you dip in your urine to determine the presence of luteinizing hormone, which stimulates the release of an egg.

The downside is that these tests can be expensive, and if your periods and ovulation are irregular, you may have to use several sticks over the course of several weeks to determine ovulation. For example, if your cycle typically ranges from 27 to 35 days, you’ll have to start testing on day 12 or 13 and keep testing until ovulation is detected, which may not happen until day 21.

There’s an 80 percent chance that after five days of use, the ovulation predictor stick will detect ovulation and a 95 percent chance it will detect it with 10 days.

To increase accuracy, do the following:

  • Follow the manufacturer’s directions precisely.
  • Test when your urine is most concentrated, such as first thing in the morning.

An egg needs to be fertilized within 12 to 24 hours after it’s released for pregnancy to occur. So, while irregular ovulation makes it harder to predict your fertile time, it doesn’t mean you won’t get pregnant. It just may be more difficult to time your fertile window.

If you’re concerned about your fertility and ovulation, see a doctor for evaluation. You may have a medical condition that affects your monthly cycle, such as:

  • premature ovarian failure
  • hyperprolactinemia, which is a condition in which the body makes too much prolactin, which inhibits ovulation
  • a typically noncancerous tumor on your pituitary gland
  • hypothyroidism
  • PCOS

If you have late ovulation and you want to get pregnant, talk with your doctor about the use of drugs such as clomiphene and letrozole that stimulate ovulation.

If ovulation is affected by an underlying condition or the use of certain drugs or medications, treating the underlying condition may improve your fertility in many cases.

If you have late ovulation, you may experience heavy bleeding when you menstruate. The hormone estrogen peaks in the first half of the menstrual cycle, causing the uterine lining to thicken and engorge with blood. Ovulation triggers the release of the hormone progesterone, which stimulates the glands housed in the uterine lining that help support a fertilized egg.

If ovulation is late or absent, estrogen continues to secrete, causing the uterine line to keep growing. Eventually the lining builds up to such an extent that it becomes unstable and sheds. That can lead to heavy menstrual flow.

See your doctor for evaluation if:

  • your cycles are fewer than 21 days apart or more than 35 days apart
  • your period stops for 90 days or more
  • your periods suddenly become irregular
  • you have heavy bleeding (you’re soaking through a tampon or pad every hour or so, for several hours)
  • you have severe or abnormal pain during your period
  • you’re concerned about your menstruation or your inability to conceive

If you have an underlying condition like PCOS or hypothyroidism, treating it can help regulate ovulation. If no cause can be determined and you want to become pregnant, your doctor may prescribe medications that help regulate ovulation. They may include:

  • clomiphene (Clomid)
  • letrozole (Femara)
  • human chorionic gonadotropins (Pregnyl, Novarel)

To improve your menstrual and reproductive health overall:

  • Don’t exercise to the extreme. Research is conflicting but very vigorous exercise may impact ovulation. However, if you’re overweight or obese, moderate exercise may improve ovulation.
  • Avoid smoking or exposing yourself to secondhand smoke. The toxins in cigarette can damage egg quality.
  • Manage stress.
  • Use barrier forms of contraception, such as condoms. These forms of birth control help protect against sexually transmitted diseases, which can reduce fertility.

Late ovulation can occur in almost any woman from time to time. Sometimes it’s temporary. Other times it may be a symptom of an underlying disorder.

Speak to a doctor or other healthcare provider if your periods are consistently irregular, your bleeding is particularly heavy, or you want to get pregnant but are having issues. Treatments are available to make ovulation more regular and increase your chances of conception, if that’s your goal.