Dealing with irregular periods can be frustrating, especially when you’re trying to expand your family. 

The typical methods for calculating ovulation may be less precise when dealing with an unpredictable cycle. However, you can still use them to gain a rough estimate of when you might be ovulating.

We’re here to help guide you through the mysteries of your monthly cycle and provide some helpful tips on identifying that elusive fertile window.

woman using a journal to track ovulation

The role of ovulation in conception

Making a baby is like a science experiment. The right ingredients must align precisely at the right moment, and then boom — conception occurs! It’s all about ovulation and timing. 

“Ovulation generally occurs approximately two weeks prior to the next menstrual cycle,” says Sandy Goodman, MD, a reproductive endocrinologist at The Reproductive Medicine Group in Tampa, Florida. 

When you ovulate, your ovary releases an egg into your fallopian tube. Although sperm can hang out in your body for three to six days, Goodman says your egg lives in your reproductive tract for about 24 hours. A healthy egg needs to meet up with healthy sperm for conception to happen

Many women trying to become pregnant use their cycle as a guide to track ovulation using the 14-day rule. “When the cycle is predictable, then we know that sometime in the middle will be when the egg is released,” says Dr. Goodman. 

Unfortunately, with an unpredictable cycle, timing ovulation is extremely difficult.

Trying to conceive with an irregular period

Having a period that doesn’t play by the rules can be annoying, but if it makes you feel better, you’re not alone. 14% to 25% of women have irregular periods that are shorter or longer than the "normal "menstrual cycle range of 23 to 35 days.

“A regular menstrual cycle can vary up to four days or so from one cycle to the next, so it would not be abnormal to have a menstrual cycle anywhere from 26 to 30 days or 28 to 32 days,” says Dr. Goodman.

According to the Cleveland Clinic, whether your period is considered normal isn’t just about its length. Other factors can signal an irregular period, such as if it lasts longer than seven days, you miss three or more periods in a row, or you experience extremely heavy or much lighter bleeding than usual.

“Ovulation trackers that we use either by urine testing or other means generally rely on a regular menstrual cycle,” says Dr. Goodman. So, having an irregular period can restrict the effectiveness of these traditional tracking methods.

woman about to put a tampon in

The calendar method

Using your calendar for cycle tracking can be helpful, but there are limitations, especially if your cycles vary in length or show up when you least expect them.

Using a period-tracking app on your phone or tablet is the easiest way to keep track of your cycle. You can also find a printable chart online. However, using this method to calculate ovulation may be inaccurate if you have irregular periods. 

“Calculations then become an average rather than being as meaningful as they are for someone who is experiencing regular cycles,” says Dr. Goodman.

Cervical mucus changes

Throughout your menstrual cycle, your cervical mucus changes, becoming clear, stretchy, and increasing around ovulation. Observing and recording these changes can help identify your fertile window if your period is regular.

Unfortunately, Dr. Goodman says checking cervical mucus isn’t a reliable ovulation indicator for women with irregular cycles, especially women with polycystic ovarian syndrome (PCOS). “They may have an elevated estrogen level throughout the month,” she adds.

Ovulation predictor kits (OPKs)

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Thanks to technology, ovulation predictor kits (OPKs) have become popular for pinpointing the best time to conceive a baby. They work similarly to a pregnancy test, using your urine to detect the luteinizing hormone (LH) surge that occurs before ovulation.

Dr. Goodman explains that irregular periods often signal the presence of PCOS, characterized by hormonal imbalances, specifically, elevated levels of LH.

“So we might be experiencing what we think is an LH surge when, in fact, it's just an elevated level in a woman who has PCOS, and that might occur multiple days during the month,” adds Dr. Goodman.

woman opening a package

Putting it all together

We'd love to provide you with the most effective method for predicting ovulation with an irregular period. Still, unfortunately, Dr. Goodman suggests that while it's possible to detect your ovulation surge, attempting to calculate ovulation independently may bring inaccurate results.

If you're feeling unsure or finding it challenging to keep track of your cycle, reaching out to your healthcare provider is a good idea. “For women who have irregular menstrual cycles, it's important to see a fertility specialist sooner rather than later because we are not able to track that ovulation and give the best effort to try to become pregnant,” says Dr. Goodman.

Remember, having an unpredictable period doesn't mean you can’t conceive — it just means you might need a little bit more help to plan your family.

Blair Sharp is a freelance writer who lives in Minnesota with her husband and son. Her words have been published in various publications, including Parents, SheKnows, The Bump, and Insider. Find her writing daily on LinkedIn and check out her weekly newsletter, Hey Freelancer! Head to her website for more.