Get all your ovulation questions answered. Learn about your ovulation cycle and determine when you are most likely to conceive.
Ovulation is when a mature egg is released from your ovary. Typically, ovulation happens about halfway through your cycle, right after the follicular phase (named for the follicles in your ovaries where eggs are developing). In reality, cycle length varies from woman to woman and so does the timing of ovulation. On average women’s cycles are between 28-35 days long, so ovulation can occur anywhere from day 14 to 18 (+/- a few days here and there depending on your cycle length).
If you’re trying to conceive, identifying ovulation will help target when you should be having baby-making sex. Your fertile window, the six day period leading up to and including ovulation day, is when you’re most likely to conceive. Sperm are persistent little fellows and can survive in the fallopian tubes for about five days, so there’s actually a little wiggle room for the egg and sperm to join. Having sex daily or every other day during the fertile window, especially the two or three days right before you ovulate, captures the time frame in which your chances of conceiving are the highest.
Ovulation itself is a quick deal, lasting about 12-24 hours for most women. This is followed by the luteal phase of your cycle, during which your uterine lining, called the endometrium, thickens to prepare for a possible pregnancy. If no pregnancy happens, then this lining is shed and you start bleeding. Your cycle begins anew!
What are the signs of ovulation?
Many women will experience ‘moliminal symptoms’ during the latter half of their cycle that is marked by ovulation to menses. These symptoms, also called premenstrual symptoms, include menstrual cramps, breast tenderness, fluid retention, and appetite or mood changes.
Ways of Tracking Ovulation
There are many ways to detect ovulation (for example, transvaginal ultrasounds in the doctor’s office or serum progesterone testing), but really only three ways to detect ovulation in a DIY fashion at home. Here are three options for finding your fertile window with tools at home and timing sex to optimize for getting pregnant:
1. Ovulation Test Kits
You can pinpoint your fertile window using ovulation tests (aka ovulation predictor kits or OPKs). The process is similar to taking a pregnancy test because the test detects the presence of hormones in urine. Most ovulation tests try to identify the LH surge (the surge of hormone that triggers ovulation) by detecting the presence of an abundance of LH in urine. Once the LH surge has occurred, ovulation usually takes place within 12 to 36 hours.
There are many types of ovulation tests—ones that you pee on directly, ones that have to be dipped into a cup of urine, ones that are digital—but they work by this same basic mechanism. Read our Ovulation Test Cheat Sheet.
2. Cervical Mucus
The cervical mucus test is a free and easy way for you to determine when ovulation is happening. It only takes about 30 seconds. Cervical mucus is the gooey, white to clear discharge produced by the cervix and found on your underwear during certain times of the month. Its consistency and color changes in response to the body’s monthly hormonal cycle, and these changes can be used to determine the fertile window. It’s not a foolproof indicator, but it’s useful data to have. For women who want to do a cervical mucus test:
- Begin recording the characteristics of your cervical mucus the day after your period stops. It’s best to chart every day for your entire cycle to get to know the different characteristics.
- Before you pee, insert a clean finger into your vagina to obtain a sample.
- Take a look and note the color (yellow, white, clear, cloudy), amount (none, some, lots), consistency (thick, sticky, stretchy) and feel (dry, wet, or slippery).
Cervical mucus becomes more abundant, stretchy, and clear around ovulation. Some compare it to a raw egg-white. The consistency of the mucus allows for sperm to swim more easily to the egg. These changes in cervical mucus are one of the body’s natural ways of helping sperm along their journey. The farther away you are from your fertile window, the more likely it is that your cervical mucus is dry, white, thick, and creamy.
Illustration from Conception 101
3. Basal body temperature (BBT)
After you ovulate, your resting body temperature increases an almost imperceptible half a degree. The progesterone that is released from the corpus luteum after ovulation actually affects a part of your brain that regulates temperature, called the hypothalamus. Progesterone increases the temperature of the body ever so slightly, and this temperature change is what we measure with the basal body temperature. You can detect this temperature change using an ultra-sensitive thermometer, called a basal body thermometer. This half a degree temperature rise confirms that ovulation has taken place. In order to catch this subtle change, the BBT has to be checked first thing in the morning while laying down.
But here’s the catch: since a woman’s body temperature increases in response to ovulation, by the time you've detected this change it’s too late to conceive in that cycle. If you have regular cycles, you can use the information from BBT to better know your cycle and help you predict when to have sex the next month.
This method is more laborious than the other two methods discussed for determining your fertile window. It’s also more prone to error, interrupted sleep, jet lag, alcohol, illness, and even stress can influence BBT readings.
How often does ovulation happen? And what causes abnormal ovulation?
Ovulation typically happens once per cycle. It’s also possible to skip ovulation completely—this is called an anovulatory cycle. Ovulating too infrequently may be a sign of fertility issues. In fact, one study found that ovulatory disorders account for at least 21% of infertility cases.
Below, are three scenarios that can result in abnormal ovulation:
1. Polycystic ovary syndrome (PCOS)
PCOS accounts for 70-85% of abnormal ovulation. Those affected have irregular, and sometimes prolonged periods and excess male hormones (androgens) that result in excess body hair (especially on the face) and cystic acne. The hormonal imbalance with PCOS prevents ovulation. PCOS has lifelong implications and can put women at increased risk for Type 2 Diabetes, cardiovascular disease, and uterine cancer. Issues with fertility related to PCOS are often addressed by changes in physical activity and diet and sometimes with medications. Read more about PCOS in Dr. Mare’s article, Getting Pregnant with PCOS: Guide & Treatment Options.
2. Primary Ovarian Insufficiency (POI; formerly known as “premature ovarian failure”)
Women with this condition are 39 years old or younger and will either have no periods or have fewer than nine per year. Laboratory testing is revealing for elevated follicle stimulating hormone (FSH) and LH, low estrogen levels, and symptoms of menopause (from the lack of estrogen) like hot flashes and vaginal dryness.
POI (which is often mistakenly referred to as “premature menopause”) accounts for 10-30% of ovulatory disorders. Usually people have symptoms unexpectedly. Some women may have an autoimmune or genetic condition that predisposes them to POI. In some cases, it is possible to become pregnant with primary ovarian insufficiency, without any medical assistance, however this is a condition that should be followed closely by a doctor.
Amenorrhea is the absence of menstruation and therefore, ovulation. And can be caused by excessive stress, exercise, or low body weight.
Hopefully after reading this you feel like you have the tools to find your fertile window! Tracking your cycle over the course of several months should help you pin down those six days leading up to and including ovulation, when you’re likeliest to conceive. If you feel like you’re getting mixed signals from your ovulation tracking, don’t hesitate to make an appointment with your health care provider to troubleshoot.