Ovulation: When It Happens, Symptoms and Fertile Days

Dr. Panagiotis Polyzos, obstetrician gynecologist in Athens
Dr. Panagiotis Polyzos MD PhD MSc

Obstetrician-Gynecologist
PhD, University of Athens Medical School

Obstetrician-gynecologist Panagiotis Polyzos practices at the Institute of Life, the IVF Unit of IASO Maternity Hospital.

Contents

Ovulation

Ovulation and fertile days

What is ovulation?

Every woman is born with hundreds of thousands of immature eggs stored in her ovaries, which later in life will start to be released each month for the purpose of fertilization. The process during which a mature egg is released from the woman’s ovaries is called ovulation. Although the term “ovulation” is widely used, the more accurate term is follicular rupture, since what actually ruptures is not the egg itself, but the follicle, the “sac” in which the egg matures.

Each month, approximately 15 to 20 eggs in each ovary begin to mature inside their follicles. Ovulation occurs when one of the ovaries releases one (or sometimes more, though less frequently) mature egg from the dominant follicle. The egg then travels into the fallopian tube, where it becomes available for fertilization.

At the same time, the endometrium (uterine lining) thickens to host the fertilized egg. If fertilization does not occur, the unfertilized egg is transported into the uterus and expelled from the body together with the endometrial lining through bleeding, known as menstruation or period. However, if fertilization does occur, the fertilized egg will continue its journey toward the uterus over the next 5 to 6 days, where it will implant into the endometrium.

Information about ovulation

  • An egg survives for about 12–24 hours after being released from the ovary.
  • It is not possible to predict which ovary will release an egg, and contrary to common belief, ovulation does not necessarily alternate between ovaries each month.
  • Usually, only one egg is released during ovulation. In cases where two or more eggs are released and fertilized, there is a possibility of a twin or multiple pregnancy.
  • Menstruation does not necessarily mean that ovulation has occurred beforehand.
  • Ovulation can be affected by stress, illness, or any disruption to a woman’s normal routine.

How often does a woman ovulate?

Some women know very well when they are ovulating. Other women do not notice any change. If you are thinking of getting pregnant, observe yourself for a few months and you will soon be able to work out your fertile days. Some small signs of ovulation are the following:

  • Tenderness and mild pain in the breasts
  • A slight discomfort or mild pain in the lower abdomen
  • Increased cervical mucus
  • A slight rise in basal body temperature, up to 1°C (1.8°F)
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How is ovulation calculated?

Learn when eggs are most likely to be released and increase your chances of conception.

First, you need to understand when ovulation will occur (the release of an egg from the ovary). There are several different methods you can try to help you identify when you are ovulating.

In one study, couples who timed intercourse around ovulation got pregnant significantly faster than is typically observed among couples trying to conceive:

  • 38% were pregnant after one cycle
  • 68% were pregnant after three cycles
  • 81% were pregnant after six cycles
  • 92% were pregnant after 12 cycles
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What are the symptoms of ovulation?

In most cases, a woman does not experience any clear symptoms before ovulation. However, in some women, symptoms may appear more noticeably and become easily recognized by the woman herself. The most common signs of ovulation may include abdominal discomfort or mild pain, as well as a very small amount of bleeding or spotting from the vagina.

In rare cases, the symptoms may be more intense or bothersome, and it is advisable to consult a gynecologist who can provide guidance and management options. What is certain is that during this time, the fertile days have arrived and the chances of achieving a pregnancy are increased.

Bleeding during ovulation

If you notice a very small amount of blood, this is generally considered a normal symptom and should not worry you. However, if the bleeding is heavier than usual or more than just spotting, it is advisable to contact your doctor for proper guidance.

What is LH (luteinizing hormone)?

The LH hormone, or luteinizing hormone, is produced by the cells of the pituitary gland and is responsible for the proper functioning of the ovaries in women. Ovulation typically occurs about 2.5 days after the increase in LH levels. Immediately afterward, the egg enters the fallopian tubes, where fertilization can take place.

Is pain during ovulation normal?

Yes, pain during ovulation is considered normal and is one of the common symptoms indicating that ovulation is beginning. For many women, however, pain may not be present at all. If the pain becomes persistent or bothersome, it is best to contact your doctor and explain your symptoms, so they can provide appropriate guidance.

Ovulation symptoms: how do I know I am ovulating

Ovulation symptoms do not appear with the same intensity in every woman. The most reliable are:

  • Change in cervical mucus: it becomes clear, slippery and stretchy like egg white. It is the best sign of the fertile days.
  • Ovulation pain: a mild twinge or heaviness on one side of the abdomen.
  • Rise in basal body temperature: by 0.2 to 0.5 °C after ovulation, so it confirms that ovulation has occurred.
  • Positive ovulation test: it detects the LH surge 24 to 36 hours before.
  • Breast tenderness, increased libido, light spotting in some women.

Symptoms of the fertile days

The fertile days are the five days before ovulation and the day of ovulation itself. The symptoms of the fertile days are essentially the symptoms of ovulation: more and clearer mucus, increased desire and, close to ovulation, a positive LH test. To calculate them with a calendar, see the guide on fertile days and the tips on how to get pregnant.

Ovulation pain and conception

Ovulation pain (mittelschmerz) is a cramp or twinge low on one side that lasts from a few minutes to one or two days. It is caused by the rupture of the follicle and a small amount of fluid that irritates the peritoneum. It shows that you are in the most fertile hours of your cycle, so intercourse on that day and the day before has the best chance of conception. The pain on its own does not mean that conception has happened. If it is severe, lasts longer or comes with period pains that are getting worse, discuss it with your doctor, because it may be a sign of endometriosis or an ovarian cyst.

Ovulation hormones step by step

The cycle is divided into two phases, with ovulation between them. Each phase is controlled by different hormones.

  • Follicular phase: from the first day of your period until ovulation. FSH from the pituitary gland stimulates a group of follicles. One of them becomes dominant and produces more and more estrogen. The length of this phase varies from woman to woman and from month to month.
  • LH peak: when estrogen reaches a high level, the pituitary releases a large amount of LH. Within about a day and a half, the follicle ruptures and releases the egg.
  • Luteal phase: the empty follicle turns into the corpus luteum and produces progesterone, which prepares the endometrium for implantation. It usually lasts 12 to 14 days. If no pregnancy occurs, the corpus luteum regresses, progesterone drops and your period comes.

This sequence explains why temperature rises after ovulation, why mucus changes before it, and why the length of the cycle is determined mainly by the first phase.

How the doctor confirms that ovulation is happening

Body signs and home tests give indications. When certainty is needed, for example when there is difficulty conceiving, the doctor uses:

  • Ultrasound follicle tracking: serial transvaginal ultrasounds show the growth of the dominant follicle and its disappearance after rupture. It is the most direct method.
  • Blood progesterone: measured about seven days before the expected period, that is around day 21 in a 28-day cycle. A raised value means ovulation has occurred. In a longer cycle, the day shifts accordingly.
  • Hormones at the start of the cycle: FSH, LH, estradiol, prolactin and thyroid hormones help find the cause when ovulation is not happening normally.

When ovulation does not happen: anovulation and its causes

A cycle without ovulation can happen to any woman occasionally. When it keeps happening, however, it is one of the most common causes of difficulty conceiving. Ovulation disorders are grouped into three main categories:

  • From the brain: the hypothalamus or pituitary gland does not send an adequate signal. This happens with low body weight, exhausting exercise, intense stress or high prolactin.
  • Hormonal imbalance with normal estrogen: the most common category, mainly represented by polycystic ovaries.
  • From the ovaries themselves: when the ovarian reserve has been depleted early, as in premature ovarian insufficiency.

Signs of anovulation are very infrequent or unpredictable cycles, absent periods, no temperature rise on the chart and LH tests that never turn positive. Treatment depends on the category. That’s why a correct diagnosis comes before any medication.

Ovulation, contraception and the morning-after pill

Combined birth control pills, the ring and the patch work mainly by suppressing ovulation. As long as you use them correctly, there is no ovulation, and the bleeding during the break is not a real period. After stopping, ovulation usually returns quickly.

The morning-after pill works mainly by delaying ovulation. That’s why it is more effective the sooner it is taken, and it does not protect you if ovulation has already happened. It does not end a pregnancy that has already implanted.

Ovulation after childbirth, during breastfeeding and in perimenopause

  • After childbirth without breastfeeding: the first ovulation can happen as early as the fourth to sixth week.
  • With exclusive breastfeeding: prolactin often suppresses ovulation, but not reliably. The first ovulation comes before the first period, so you can get pregnant before you see a period.
  • In perimenopause: cycles without ovulation become more frequent and periods may become heavier or unpredictable. Conception is less likely, but not impossible until you have gone a full year without a period.

When mid-cycle pain needs urgent evaluation

Mild ovulation pain is harmless. Rarely, however, a follicle or corpus luteum can bleed into the abdomen, or the ovary can twist (ovarian torsion). Seek medical help right away if you have:

  • sudden, very severe pain that does not ease with simple painkillers,
  • dizziness, fainting, rapid heartbeat or paleness,
  • shoulder pain together with abdominal pain,
  • vomiting or fever together with the pain.

If there is a chance of pregnancy, the same pain may be due to an ectopic pregnancy. That’s why a pregnancy test is the first step at the hospital.

Frequently Asked Questions

Is bleeding at ovulation normal?

Yes. Light mid-cycle bleeding, pink or brown, occurs in a small percentage of women and is due to the temporary drop in estrogen. If it is heavy, happens often or comes with pain, a gynecological checkup is needed.

Usually from a few hours to two days, and it is just a few drops. Bleeding that lasts longer or looks like a period is not considered ovulation bleeding.

The five days before ovulation and the day of ovulation. In a 28-day cycle, this corresponds roughly to days 10 to 15. In a longer or shorter cycle, ovulation happens about 14 days before the next period.

Mild pain low in the abdomen, usually on one side and sometimes radiating to the lower back, is common. Dizziness is not a typical symptom. If it is intense or keeps recurring, discuss it with your doctor.

Yes. Anovulatory cycles are common in adolescence, in perimenopause and in polycystic ovary syndrome (PCOS). If your cycle is very irregular, it is worth having your ovulation checked.

Clear, stretchy cervical mucus, mild pain on one side of the abdomen, breast tenderness, increased libido and a small rise in basal body temperature after ovulation.

Usually from a few minutes to 24 to 48 hours. If it lasts longer or is very severe, a gynecological checkup is needed.

Not necessarily. The pain shows that you are in your fertile hours, not that conception has happened. The chance is higher when intercourse takes place the day before and the day of ovulation.

Rarely, two eggs may be released within the same time window, usually within 24 hours, and this explains fraternal twins. Two separate ovulations weeks apart in the same cycle do not happen under normal conditions.

With correct use of combined birth control pills, ovulation is suppressed. Missed pills, vomiting or interactions with certain medicines may allow ovulation.

Signs are very infrequent or unpredictable cycles, absent periods and ovulation tests that never turn positive. Confirmation is done by measuring progesterone in the second phase of the cycle or with ultrasound follicle tracking.

Exclusive breastfeeding often delays the return of ovulation, but does not rule it out. The first ovulation happens before the first period, so you need contraception if you are not planning another pregnancy.

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