What is ovulation & how to tell when it happens
It's easy to think the main event of the menstrual cycle is the period (thanks to the bleeding, cramping and mood changes), but the much quieter ovulation is an equally important event. Knowing when you ovulate is key to understanding many aspects of sex and reproductive health, like the “fertile window” (the most likely time frame to get pregnant during your cycle) and how many birth control methods (including the morning-after pill) work.
So the big question is: how can you tell when you’re ovulating? We’re covering all things ovulation, including what it is, when it's most likely to happen, physical clues that signal ovulation and how to keep track of it (if you so desire).
What is Ovulation?
Ovulation is a core part of both the menstrual cycle and the reproductive process. Let’s start with ovulation and the menstrual cycle.
Ovulation describes the release of an egg from an ovary. From there, the egg travels down the fallopian tube and stays there for 12-24 hours. The vast majority of the time, the egg will disintegrate or pass quietly out of the uterus.
Ovulation, though brief, is a pivotal part of the menstrual cycle and the hormones that drive it. A single menstrual cycle starts on the first day of your period (considered “day 1”). Ovulation is triggered by something called the LH (lutenizing hormone) surge, which typically occurs about two weeks into the menstrual cycle (around “day 14”). Once the egg has disintegrated or passed from the uterus, the body prepares for its next period. Hormone signaling tells the uterus lining to freshen up and essentially get rid of the top layers. The signaling and preparation to remove the top layers takes about two weeks, and the lining comes out in the form of a period. This results in another period and “day 1” of the next menstrual cycle.
Ovulation and Pregnancy
Ovulation that leads to pregnancy comes down to timing of sex and optimal conditions. While sex in the days leading up to and during ovulation will not always result in pregnancy, this is the time in your menstrual cycle when you’re most fertile and, therefore, have the highest probability of becoming pregnant. To get a better sense of the process, here's a quick timeline:
- Eggs develop in follicles in your ovaries
The follicular phase is the first stage of each menstrual cycle. This is when the body releases follicle-stimulating hormone (FSH) to help eggs mature inside tiny sacs in your ovaries (called follicles). The follicles prepare multiple eggs, but only one will be released.
- One follicle becomes dominant
As your cycle progresses, a few developing follicles are considered candidates. Eventually, one follicle emerges as the dominant candidate, continuing to mature while the others regress.
- Release of an egg
When the dominant egg is sufficiently mature, the follicle will release it into the fallopian tube. This is ovulation and is stimulated by a surge in luteinizing hormone (LH) levels.
- Fertilization and implantation
Following release, the egg remains viable (usable) for about 12 to 24 hours. During this period, if the egg encounters a sperm in the fallopian tube, fertilization can occur. The fertilized egg then travels down the fallopian tube and reaches the uterus within 6 to 12 days for implantation into the uterine lining. If the fertilized egg implants into the uterus and continues to develop, then a pregnancy has begun.
- No fertilization
If the egg does not encounter a sperm in the fallopian tube, it will not be fertilized. At this point, the egg will disintegrate or pass from the uterus after 12-24 hours.
Fun Facts About Your Menstrual Cycle and Ovulation
Everyone's cycle is different. There are a lot of factors that can influence its timing and schedule, like diet, stress, travel and exercise. However, it’s called a “cycle” because your period and ovulation should usually happen around the same time from one cycle to the next. This is because hormones drive this entire process, and their rises and falls are pretty darn precise. They also have some subtle and not-so-subtle side effects that, if you’re paying attention, may help you figure out exactly where you are in your cycle.
Phases of the Menstrual Cycle
There are four phases of the menstrual cycle:
The menstrual cycle officially kicks off with menstruation. This is when the uterus sheds its lining and some blood is lost, producing your period.
The Follicular Phase
This phase also begins on the first day of menstruation and encompasses the entire menstruation period through ovulation. During this phase the brain slowly ramps up the release of FSH. FSH does two things: it prepares the egg for ovulation and causes release of estrogen from the ovaries. This phase concludes with ovulation.
Ovulation typically occurs around the middle of the menstrual cycle, approximately 14 to 15 days after the first day of your period. Rising estrogen levels will trigger your brain to release LH very quickly (called the LH surge) which in turn causes ovulation.
The Luteal Phase
During the luteal phase, the now-empty follicle (in the ovary) changes into a corpus luteum and releases progesterone and estrogen. These hormones will fluctuate depending on the presence or absence of implantation (whether or not a fertilized egg has stick to the wall of the uterus). If you become pregnant, your body will begin producing human chorionic gonadotropin (hCG), which is the hormone that is detectable with pregnancy tests. If you don't become pregnant, your body will prepare for your next period, which usually happens about 14 days after ovulation. And the cycle starts all over again.
How long does ovulation last?
Ovulation itself doesn't actually last that long—it’s usually over within 12- 24 hours. However, the 5 days leading up to and the 24 hours after ovulation are considered your “fertile window,” the timeframe within which conception can occur. The five days before ovulation are within that window because sperm can survive up to five days in the female reproductive tract.
When does ovulation occur?
The length of the menstrual cycle influences the timing of ovulation. In a typical 28-day cycle, ovulation would occur around day 14. But cycle lengths can vary, which can affect the timing of ovulation. Other factors can influence the duration and regularity of your cycle as well, like stress, exercise, travel, change in routine, smoking, illness, and more.
Other weird but fun facts about ovulation:
- You're hotter, literally: You may experience an increase in body temperature during ovulation, making you slightly warmer.
- You're hotter, figuratively: According to studies, men found their female partners more attractive during their fertile phase. Women might also feel sexier during ovulation.
- And you're hornier: Hormonal estrogen is high during your ovulation stage, and yes, it can definitely increase your sex drive. You may feel an increased sex drive during the days before ovulation and the day of.
How Do You Know When You're Ovulating?
There are a few different ways to determine when you're ovulating. Schedule tracking methods will be discussed first, and signs and symptoms will follow. Keep in mind that no two bodies are the same, and one person’s ovulation experience may be different than the next.
Track your cycle
Tracking your menstrual cycle is the most common method. This involves keeping a record of your periods' start and end dates over several months to identify patterns. Ovulation happens, on average, 14 days before your next period.
The calendar method is used to determine your fertile window. It requires tracking your period for 6 to 12 cycles and identifying your longest and shortest cycle duration. From the total days of your shortest cycle, subtract 18. This is considered the first fertile day of your cycle. From the total days of your longest cycle, subtract 11. This is considered the last day of your fertile window.
The calendar method works best for a menstrual cycle that is somewhat regular. It also requires recalculation if your cycle duration changes at any point in time.
A variation of the calendar method, the standard days method works best for people with consistent cycles that last between 26 and 32 days. It identifies a fixed fertility window between days 8 and 19 of the menstrual cycle. Some track it using apps or even a bracelet or necklace with corresponding beads.
There are a lot of things happening in your body during the ovulation phase, some of which people are able to feel and see. Here are some symptoms to be aware of that can help you identify if and when you’re ovulating.
Cervical mucus changes
In the days before and after ovulation, cervical mucus (vaginal discharge) can be white or off-white, thin and watery or dry and tacky. However, as ovulation approaches, cervical mucus becomes clear, mucus-like, slippery, and stretchy, resembling egg whites. This fertile mucus facilitates the passage of sperm into the uterus and can show up in your underwear or when you wipe.
Mild pelvic discomfort or cramps can occur during ovulation. Depending on which ovary releases the egg, it might be felt on either your left or right side. This phenomenon, known as mittelschmerz (meaning "middle pain" in German), can be a physical indicator of ovulation. The pain usually lasts no longer than 24 hours.
Basal Body Temperature Method (BBT)
Your BBT rises slightly (like ½ a degree) after ovulation due to increased progesterone levels. To find out when you ovulate, take your temperature with a digital thermometer around the same time every morning before getting out of bed. Track these temperatures over the course of a few cycles and see if you identify a pattern. Ovulation will happen right before a rise in BBT. You’re most fertile about 2-3 days before your temperature rises.
Changes in saliva
A change in saliva can happen during ovulation. Though it’s unlikely you’ll notice a difference, this change is used by many home ovulation kits. When it's observed under a microscope, the saliva has fern-like patterns. This is associated with increased estrogen levels (seen about 24 hours before ovulation).
Did you have unprotected sex during or close to ovulation and don't want to get pregnant? Julie can help.
If you're not tracking your menstrual cycle, it can be hard to know when ovulation will come. And if you happen to have unprotected sex around this time, trying to figure out if you were ovulating or if you were about to ovulate can feel stressful. To prevent pregnancy after unprotected sex, take Julie, an over-the-counter morning-after pill, ASAP. It can help prevent pregnancy if taken within 72 hours of unprotected sex. Julie will not work if you’ve already ovulated. Find out more about Julie effectiveness during ovulation.
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Although the information above may be useful, it shouldn’t replace the advice of your healthcare professional. For questions about emergency contraception or birth control, please talk to your healthcare professional.