When Is a Woman Most Fertile?
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 get pregnant.
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. Ovulation is a key event in your cycle and it occurs on approximately Day 14 of an average 28-day menstrual cycle.
Your most fertile days ("the fertile window") are the 3 days leading up to and including ovulation. This is when you’re most likely to get pregnant. So, having sex then gives you the best chance of ensuring the egg is fertilized by sperm so you 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. So, rather than thinking in terms of Day X of your cycle, look for the symptoms described below.
Ovulation: What Is it?
During reproductive ages, the ovary releases an egg every month. This event occurs when ovary follicles rupture and release the oocyte which travels to the fallopian tube and becomes an ovum.
The rupture of the ovary follicles can cause some light spotting and some can even feel it happen in their body. However, for the vast majority of women, the moment usually goes unnoticed.
After the oocyte is released from the ovary, it moves into the fallopian tube. At this point it is called an ovum . The egg stays in the fallopian tube for about 24 hours, waiting for a single sperm to fertilize it.
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 fertilize your ovum, resulting in pregnancy.
What’s Age Got to Do With it?
Of course, fertility is impacted by many other 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 high quality eggs.
According to 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 here's a less than 10% chance of getting pregnant within each menstrual cycle.
Signs of Ovulation
Ovulation usually goes unnoticed in many but there are some symptoms that most women can learn to track or pay attention to so you can keep an ovulation calendar. These include your basal body temperature, cervical music 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's advisable to take your temperature to understand 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.
If your cervical mucus is...
- Dry or sticky: It’s unlikely you’re ovulating
- Creamy cervical mucus: Ovulation may be coming
- Wet or watery: Ovulation may start soon
- Wet and stretchy (eggy white texture): You may be at your day of ovulation
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 guide on Flo’s website.
You May Experience Slight Twinge or 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 your 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 it may definitely mean that you may experience an increased libido when ovulation occurs.
According to a report on Psychology Today, "ovulating women do clearly increase their sexual desire, and they do increase the frequency with which they have sex with their current partners.”
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, who need to identify the "fertile window."
An ovulation predictor kit (also sometimes called an OPK) is a test that detects the presence and concentration of luteinizing hormone (LH) 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.
You'll know if pregnancy has occurred by administering a pregnancy test. Or if your next period doesn't come when it's due according to your periods calculator. 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.
- Supplements and lifestyle changes: Your doctor may advise you to take some supplements, like folic acid, before you get pregnant.
- 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, a male partner will also need fertility testing.