Most women ovulate once per menstrual cycle, which typically means about 12 to 13 times a year. Ovulation happens when one of the ovaries releases a single egg, and in an average 28-day cycle, this occurs roughly midway through. But “once a month” is a simplification. Cycle length varies from person to person and even month to month, and several factors can cause you to ovulate less frequently or not at all.
What Happens During a Typical Cycle
In the days leading up to ovulation, rising levels of a specific hormone trigger the ovary to prepare an egg for release. About 36 to 40 hours after this hormone surge, the egg is released from the ovary and enters the fallopian tube. This is the single event most people mean when they talk about ovulation.
The average menstrual cycle is 28.1 days, but a large study published in JAMA found a standard deviation of nearly 4 days, meaning cycles anywhere from about 24 to 32 days are common and normal. Shorter cycles mean you ovulate slightly more often per year; longer cycles mean slightly less often. What matters is that ovulation generally happens once per cycle, regardless of how long that cycle runs.
When You Might Ovulate Less Often
Not every cycle produces an egg. Cycles without ovulation, called anovulatory cycles, happen to most women occasionally and become more common at certain life stages.
Polycystic ovary syndrome (PCOS) is one of the most common reasons for infrequent or absent ovulation. In one large study of women with PCOS, roughly 88% were not ovulating regularly. Women with PCOS often have longer, irregular cycles, which means fewer ovulations per year and reduced fertility without treatment.
Other factors that can suppress ovulation include significant weight loss or gain, high stress, thyroid disorders, and excessive exercise. In these cases, the brain may not send the hormonal signals the ovaries need to release an egg, even though the reproductive system is otherwise healthy.
How Age Changes the Pattern
Ovulation is most consistent during your 20s and early 30s. As you move into your late 30s and 40s, the transition toward menopause (perimenopause) gradually disrupts the pattern. During early perimenopause, your cycle length may shift by seven days or more from what you’re used to. You may start skipping ovulation in some cycles entirely, even if you still get a period.
In late perimenopause, gaps of 60 days or more between periods are common, meaning you might ovulate only a handful of times per year. This phase can last several years before periods stop completely at menopause, after which ovulation no longer occurs.
Can You Ovulate More Than Once Per Cycle?
Yes, though it’s uncommon. Some women release two or more eggs in a single cycle, a process called hyperovulation. When two eggs are released and both are fertilized, the result is fraternal twins. The tendency toward hyperovulation runs in families and becomes slightly more likely with age, which is one reason twin rates increase for women in their 30s. When multiple eggs are released, it happens within the same narrow window of time, not weeks apart within a single cycle.
How Hormonal Birth Control Affects Ovulation
Combined hormonal contraceptives (the pill, patch, or ring) work primarily by preventing ovulation altogether. They suppress the hormonal signals that trigger egg development and release, so while you’re using them consistently, you typically ovulate zero times per year. The risk of breakthrough ovulation is highest during the placebo or hormone-free interval, especially if you’re late starting your next pack.
The degree of ovulation suppression depends on the specific formulation, the dosage, and how consistently you take it. With lower-dose pills, follicle development can resume within just two to three days of missing doses, which is why timing matters more with these formulations.
After Pregnancy and While Breastfeeding
Ovulation doesn’t resume immediately after giving birth. For women who are exclusively breastfeeding day and night with no supplemental feeding, ovulation is typically suppressed for up to six months postpartum. This works because breastfeeding alters the hormones that drive the ovulatory cycle. The suppression is most reliable when the baby feeds frequently, with no more than four hours between daytime feeds and six hours overnight.
For women who aren’t breastfeeding, ovulation can return as early as four to six weeks after delivery. This means pregnancy is possible again well before your first postpartum period, since ovulation happens before bleeding resumes.
Signs That Ovulation Is Happening
Your body provides a few observable clues. The most reliable one is a change in cervical mucus. In the days leading up to ovulation, rising estrogen causes mucus to become slippery, stretchy, and similar in appearance to raw egg whites. This texture helps sperm travel more easily toward the egg. After ovulation, the mucus typically becomes thicker and less noticeable.
Some women also feel a brief, one-sided twinge of pain in the lower abdomen around the time of egg release. A slight rise in resting body temperature after ovulation is another sign, though it only confirms ovulation after the fact. Over-the-counter ovulation predictor kits detect the hormone surge that precedes egg release by about a day and a half, giving a more precise heads-up.
The Fertile Window Is Narrow
Once released, an egg survives for less than 24 hours. Sperm, by contrast, can live inside the reproductive tract for up to five days. This means your fertile window in any given cycle is roughly six days: the five days before ovulation plus the day of ovulation itself. Outside that window, conception isn’t possible, no matter how regular your cycles are. For women with irregular cycles, pinpointing this window is harder, which is why tracking mucus changes or using predictor kits can be useful if you’re trying to conceive or avoid pregnancy.