When you’re ovulating, one of your ovaries releases a mature egg into the fallopian tube, where it can be fertilized for the next 12 to 24 hours. This happens roughly midway through your menstrual cycle and is the result of a precise hormonal chain reaction that also produces several noticeable physical changes, from shifts in cervical mucus to mild pelvic pain. Here’s what’s actually going on in your body during this process.
The Hormonal Chain Reaction
Ovulation doesn’t happen spontaneously. It’s triggered by a sharp spike in luteinizing hormone (LH), produced by the pituitary gland in your brain. This spike, called the LH surge, begins about 36 hours before the egg is actually released and lasts roughly 24 hours. Ovulation itself occurs between 8 and 20 hours after LH reaches its peak. This is why ovulation predictor kits, which detect LH in your urine, can give you a heads-up that ovulation is coming within 12 to 48 hours.
Before the LH surge kicks in, rising estrogen levels set the stage. Throughout the first half of your cycle, a dominant follicle (a small fluid-filled sac in one of your ovaries) grows and produces increasing amounts of estrogen. When estrogen reaches a critical threshold, it signals the brain to release that flood of LH. It’s a tightly coordinated conversation between your brain and your ovaries, and the timing has to be right for the egg to mature and release properly.
What Happens Inside the Ovary
The dominant follicle has been growing for days, nurturing the egg inside it. When the LH surge arrives, it triggers enzymes that break down the outer wall of the follicle. The follicle essentially ruptures, and the mature egg slips out into the space near the fallopian tube. Tiny finger-like projections at the end of the tube sweep the egg inside, where it begins its journey toward the uterus.
Once the egg is gone, the leftover follicle doesn’t just disappear. It transforms into a temporary structure called the corpus luteum, a yellowish mass of cells that takes over hormone production. Its primary job is pumping out progesterone, which thickens and prepares the uterine lining to support a potential pregnancy. If the egg isn’t fertilized, the corpus luteum breaks down after about 10 to 14 days, progesterone drops, and your period begins.
Changes in Cervical Mucus
One of the most reliable signs that ovulation is approaching is a change in your cervical mucus. In the days leading up to ovulation, rising estrogen causes the mucus to become slippery, stretchy, and clear, often compared to raw egg whites. You can test this by pressing the mucus between two fingers and gently pulling them apart. Fertile mucus will stretch without breaking easily.
This consistency isn’t random. The egg-white texture creates a friendlier environment for sperm, helping them swim through the cervix and survive longer in the reproductive tract. After ovulation, progesterone takes over and the mucus becomes thicker, stickier, and less transparent, essentially closing the window.
Your Fertile Window Is Wider Than You Think
The egg itself only survives 12 to 24 hours after release. That’s a narrow target. But because sperm can survive inside the uterus and fallopian tubes for 3 to 5 days, your actual fertile window stretches to about six days: the five days before ovulation plus the day of ovulation itself. This means sex that happens days before you ovulate can still result in pregnancy, since sperm may already be waiting in the fallopian tube when the egg arrives.
Physical Symptoms You Might Notice
Not everyone feels ovulation happening, but many people experience at least some of these signs.
Pelvic Pain
A mild, one-sided pain in your lower abdomen around mid-cycle is sometimes called mittelschmerz (German for “middle pain”). It can feel dull and achy like a menstrual cramp, or sharp and sudden. The pain is typically on the side of whichever ovary is releasing the egg that month. For most people, it lasts anywhere from a few minutes to a few hours, though it occasionally lingers for a day or two. Some people get it every cycle, others rarely or never.
Breast or Nipple Tenderness
The hormonal shifts around ovulation can make your breasts feel sore or your nipples sensitive. Before ovulation, high estrogen levels can stimulate breast tissue. Shortly after, the sudden drop in estrogen and rise in progesterone can trigger similar discomfort. This tenderness is usually mild and temporary.
Light Spotting
A small amount of vaginal bleeding or pinkish discharge around ovulation is normal for some people. It’s thought to be related to the rapid hormonal shifts or the rupture of the follicle itself.
Increased Sex Drive
Many people notice a bump in libido around ovulation, driven by the peak in estrogen and the LH surge. From an evolutionary standpoint, this makes sense: your body is nudging you toward sex during the window when conception is possible.
The Temperature Shift
Your resting body temperature (called basal body temperature) rises slightly after ovulation, typically by less than half a degree Fahrenheit, or about 0.3 degrees Celsius. This bump is caused by progesterone from the newly formed corpus luteum. The catch is that the temperature increase happens after the egg has already been released, so it confirms ovulation rather than predicting it. To use this method for tracking, you need to measure your temperature first thing every morning before getting out of bed and look for the sustained rise over several cycles to identify your pattern.
Because the shift is so small, it’s easy to miss without a sensitive thermometer. Illness, poor sleep, or alcohol the night before can all throw off the reading. Many people combine temperature tracking with cervical mucus observation for a more complete picture of their cycle.
What Varies From Cycle to Cycle
Ovulation doesn’t always happen on day 14. That number assumes a textbook 28-day cycle, but cycles commonly range from 21 to 35 days, and ovulation timing shifts accordingly. Stress, illness, travel, significant weight changes, and intense exercise can all delay or suppress ovulation in a given month. Some cycles are anovulatory, meaning no egg is released at all, and you may still get a period (or what appears to be one) afterward.
The ovary that releases the egg isn’t strictly alternating either. While both ovaries participate, it’s not always a neat left-right-left pattern. One ovary may release eggs several months in a row. This is why mittelschmerz can show up on the same side for multiple cycles before switching.