Boosting Your Odds: When Is a Woman Most Fertile?
This article was medically reviewed by Dr. Navya Mysore and updated on March 8, 2024
If you're trying to get pregnant, or simply seeking a better understanding of your body and menstrual cycle, it's valuable to learn about fertility and to understand your fertile days, i.e. when you're most likely to conceive.
Understanding Your Cycle and Fertile Days
If you want to get pregnant or to learn more about when you're fertile it really starts with understanding your entire menstrual cycle. Most women are acutely aware of their period (the first day of your period is the first day of your cycle), but they may be less familiar with the other events in their menstrual cycle.
The first day of your menstrual cycle is counted from the first day of your period and ends at the beginning of your next period. The average cycle length is 28 days, but can vary from 21 days to 35 days. Ovulation is a key event in your cycle and it occurs approximately day 14 of an average 28-day menstrual cycle.
Your most fertile days ("the fertile window") are the 5 days leading up to and including ovulation. Ovulation can occur for up to 48 hours, which results in a total of 7 possible fertile days. This is when you’re most likely to get pregnant. Having sex during this phase gives you the best chance of ensuring the egg is fertilized by sperm so you can become pregnant.
It’s worth noting that many women do not have a cycle length of 28 days and even if they do have a regular cycle, when you ovulate can be impacted by many factors, from stress to jetlag, smoking and illness. Rather than just tracking your period and going by day X of your cycle, it can be helpful to track ovulation symptoms as well.
Ovulation: What Is it?
During the age of reproduction, the ovary releases an egg every month. This event occurs when ovarian follicles rupture and release an oocyte which travels to the fallopian tube and becomes an egg or ovum.
The rupture of the ovarian follicles can cause some light spotting. Some can even feel it happen, as it can present itself as pelvic cramping. However, for the vast majority of women, the moment usually goes unnoticed.
Once the oocyte reaches the fallopian tube and becomes an egg, it stays there for about 24 hours.
If the egg is not fertilized by sperm during that time (and pregnancy does not occur), it disintegrates (breaks down) and menstruation (your menstrual period) begins 11-16 days later.
It's worth noting that a man's sperm can live 3-5 days after sexual intercourse. This means that even though you’re not ovulating when you have intercourse, if you are fertile 5 days later the sperm can still potentially fertilize your ovum, resulting in pregnancy.
What’s Age Got to Do With it?
Of course, fertility is impacted by many factors. Lifestyle and other health conditions can have an effect on fertility.
But one of the biggest factors that impacts pregnancy is age. Your odds of getting pregnant are highest in your 20s and 30s, as this is when women are technically the most fertile and have higher quality eggs.
According to the American College of Obstetricians and Gynecologists (ACOG), after age 37, a woman's odds of becoming pregnant decreases rapidly. By the time a woman turns 40 there is a less than 5% chance of getting pregnant within each menstrual cycle.
Signs of Ovulation
Ovulation usually goes unnoticed for many but there are some symptoms that most women can learn to track or pay attention to so you can keep an ovulation calendar. Ovulation symptoms can include a change in your basal body temperature, cervical mucus, and more.
Your Basal Temperature Falls
One of the most objective symptoms is that your basal body temperature drops a little bit just before your egg is released from your ovary. Then, 24 hours later, your basal temperature rises and stays up for several days. If you're trying to get pregnant, it can be very helpful to track your period and that way track ovulation and symptoms that go along with it.
To better understand when you’re ovulating, you can also track your basal body temperature—though, one important consideration is measuring your temperature every morning at the exact same time. Throughout the day, our body temperature changes for a number of reasons: the ambient temperature, if you’ve exercised, or just eaten a meal.
Taking your temperature at the same time each day as you wake up will give you consistent temperatures so you can spot a difference when you’re ovulating.
According to Healthlink BC your basal body temperature averages between 36.1°C (97°F) and 36.4°C (97.5°F) before you ovulate. It averages 36.4°C (97.6°F) to 36.4°C (97.6°F) after you ovulate.
Discharge Changes When You Ovulate
The changes in your cervical mucus over the course of your menstrual cycle also hold clues about when you might be ovulating.
It's hard to track your cervical mucus if you are wearing different color and texture underwear every day. It can be helpful to use a white thin pantyliner so you can observe the changes going on with your vaginal discharge so you can better understand your cervical mucus.
If your cervical mucus is...
- Dry or sticky: It’s unlikely you’re ovulating
- Creamy cervical mucus: Ovulation may be coming
- Wet and stretchy (eggy white texture): You may be at your ovulation day
Your Cervix Softens and Opens Up
As you approach your most fertile time, your cervix softens. This is sometimes known as having a short, high, open and wet cervix.
For a step-by-step guide to checking your cervix position, visit this helpful guide. It can be challenging to understand how to examine your cervix and know what you’re feeling. Some of the other ovulation symptoms may be easier to track and that’s totally OK!
You May Experience Pelvic Cramping
Mittelschmerz translates literally as “middle pain” and is the name for the slight twinge or cramp that some women experience when the follicle releases the egg on the day of ovulation during their menstrual cycle.
For many women, there is no sensation whatsoever.
According to the Mayo Clinic “Mittelschmerz pain occurs on the side of the ovary that's releasing an egg (ovulating). The pain may switch sides every other month, or you may feel pain on the same side for several months.”
Some Light Spotting May Occur When You Ovulate
When the ovaries release the egg, a tiny follicle ruptures to allow the egg to be released. This can be a cause of spotting for a day or so.
For some women, spotting that occurs around the time of ovulation is light red or pink in color. This is because we also produce more cervical fluid around the time of ovulation and the blood gets mixed with that fluid, causing it to be a lighter shade.
Increased Libido or Sex Drive
The most well-known sign of ovulation is an increased sex drive. It’s important to know that this does not mean you’ll only want to have sex during ovulation, but you may experience an increased libido when ovulation occurs.
How Long Do You Ovulate For?
Ovulation or the “fertile window” lasts between 12 and 24 hours. That's how long the egg released by the ovary is viable for fertilization.
How to Know Your Fertile Window: Ovulation Predictor Kits
In addition to tracking the signs of ovulation listed above, there’s another step you can take to predict your fertile window. This is especially helpful for those who want to increase their chance of getting pregnant and need to identify their "fertile window."
An ovulation predictor kit is a test that detects the presence and concentration of luteinizing hormone (LH) and/or estrogen in your urine. Between 12-48 hours on average before ovulation, there is a brief surge in LH levels. Ovulation predictor kits may be especially helpful for women who want to have the best chance of pregnancy.
If you miss your period, then you could be pregnant! You can confirm this with a urine pregnancy test. If you're planning to get pregnant it's always worth talking with your doctor to ensure you and your partner are setting yourselves up for success.
Some of the things you should discuss:
- Stopping birth control: If you've been on birth control, you should discuss how to stop taking it to prepare for conception.
- Supplements and lifestyle changes: Your doctor will advise you to start supplements, like folic acid, or a prenatal vitamin before you get pregnant (and continuously during pregnancy, as well).
- Current medications: If you're on any other medications, you'll want to discuss them with your doctor in light of a possible pregnancy.
- Fertility questions: If there are suspected fertility problems, you may want to get ahead of them at the start of fertility testing. If fertility testing needs to be done earlier, your health care provider can help navigate your care. Otherwise, fertility testing is only initiated after 12 months of trying to conceive for women under 35 years old, and 6 months for women over the age of 35 years old.
Sources:
https://www.healthline.com/health/womens-health/stages-of-menstrual-cycle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC27529/
https://myhealth.alberta.ca/Health/pages/conditions.aspx?hwid=hw202058
https://my.clevelandclinic.org/health/body/21957-cervical-mucus
https://www.mayoclinic.org/diseases-conditions/mittelschmerz/symptoms-causes/syc-20375122
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We hope you found this post informative—but remember: we’re not doctors and this post is not medical advice! While all posts are fact-checked and well researched, we always recommend you chat with your doctor about any questions or concerns you might have regarding a medical condition.
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