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How irregular periods impact your ability to get pregnant

How irregular periods impact your ability to get pregnant

7 min read

The unpredictability of irregular periods can be frustrating for anyone, but what about when you’re trying to conceive? Not being able to easily track your menstrual cycle and find your fertile window can add an obstacle on the path to pregnancy, but that doesn’t mean conception won’t happen.

To better understand irregular periods and how they can impact fertility, we sat down with OB-GYN and Modern Fertility medical advisor Dr. Jennifer Conti, MD, MS, MSc. Keep reading for the answers to the following questions:

  • When it comes to period length and frequency, what’s considered irregular?
  • How can irregular periods impact fertility and getting pregnant?
  • If you use birth control to regulate your periods, what should you do when you’re trying to conceive?
  • How can you increase your chances of getting pregnant when you have irregular periods?
  • Do you need to talk to your doctor if you’re trying to get pregnant and have irregular periods?
  • What fertility treatments can help when you have irregular periods?

When it comes to period length and frequency, what’s considered irregular?

No two people have identical menstrual cycles, but there are standard parameters of regular versus irregular periods — specifically the length of time between periods, the number of days of bleeding, and the consistency of your periods from cycle to cycle.

Exactly what’s considered “normal” for period length and frequency varies among even the most reputable sources. The American College of Obstetricians and Gynecologists (ACOG) and the Office on Women’s Health (OWH) write that 28 days is “typical” for a menstrual cycle, but though OWH specifies that cycle length can vary from month to month and periods are still “regular” if they usually come every 24-38 days. In terms of period length, ACOG says "up to 8 days" and OWH says 4-8 days. The Mayo Clinic, on the other hand, reports that menstrual bleeding typically occurs every 21–35 days and lasts 2–7 days, but “within a broad range, ‘normal’ is what’s normal for you.” Shorter or longer cycles or periods beyond the above ranges might warrant a trip to your healthcare provider.

According to Penn Medicine, it’s also time for a check-in if you experience any of the following:

  • Sudden changes to how often you get your period
  • Bleeding between periods (aka spotting)
  • An unusually heavy period (i.e., you have to change your menstrual product more than once every four hours)
  • Bleeding for more than a week
  • Extremely painful periods
  • No period for 90 days

How can irregular periods impact fertility and getting pregnant?

25% of all female infertility problems among people with ovaries can be attributed to irregular or abnormal ovulation — which, in turn, leads to irregular periods. Dr. Conti says that one of the most difficult aspects of trying to conceive with irregular periods is not being able to time sex or insemination around when you’re most likely to get pregnant. According to Dr. Conti, this intentional timing is the “best way for sperm to meet the egg” and result in conception.

Why do irregular periods make that difficult? If you don’t know when you might ovulate (aka when your ovary will release an egg for fertilization), you won’t be able to pinpoint your fertile window: the five days leading up to and the day of ovulation. But by tracking your cycle, no matter how irregular it is, or by seeking medical assistance if necessary, it’s definitely possible to get pregnant.

If you use birth control to regulate your periods, what should you do when you’re trying to conceive?

There are many reasons to use birth control to regulate your period. For example, endometriosis, a disorder in which uterine lining grows outside of the uterus, and PCOS, a hormonal disorder that causes irregular ovulation, are frequently managed by hormonal birth control. (Specifically, hormonal birth control helps with pain management during heavy periods caused by endometriosis or helps reduce the uterine lining buildup associated with PCOS and anovulation.)

But what if you’re trying to get pregnant? Dr. Conti says this is a moment in your fertility journey when you should reach out to your healthcare provider to discuss alternative treatments. If you live with endometriosis, you might be able to start taking over-the-counter medicines like Advil or Motrin for pain relief. If you have PCOS and have irregular ovulation, you may start taking an ovulation-inducing medication like Letrozole, which is helpful in multiple ways since it can also help you get pregnant — more on that in the next section.

How can you increase your chances of getting pregnant when you have irregular periods?

Keeping track of ovulation and your cycle with ovulation predictor kits (OPKs) can be helpful even when you have irregular periods. OPKs like the Modern Fertility Ovulation Test work by measuring levels of luteinizing hormone (LH) in your urine, which Dr. Conti explains is “a hormone that is produced in your brain and tells your ovary to ovulate.” Since OPKs detect LH in your urine, your results can help you predict ovulation and your fertile window.

When your period is irregular, OPKs can help you essentially keep a diary of the times you may be ovulating, allowing you to collect data about your own body that can be shared with an OB-GYN or reproductive endocrinologist if you’re having trouble getting pregnant. “You can be an active partner in your healthcare and gather information before you even visit your doctor, which then helps your doctor treat you because you have information about your cycle,” Dr. Conti says.

OPKs can also help you better understand your ovulation patterns so you can plan for trying to conceive in the future. For example, you might learn that you may actually ovulate every three months, so you can time sex or insemination around that schedule. (Even if you don’t want to get pregnant in the future, tracking your ovulation can be an effective way to better understand your reproductive health in general — we dive into that more here!)

OPKs can be incredibly useful when you have an irregular period, but it’s important to remember they can only help you predict ovulation based on your LH levels — not confirm that ovulation has definitely happened. But, as Dr. Conti explains, “People with anovulatory bleeding or PCOS have higher rates of false positives from [most] OPK results because your LH may surge but your ovary may not release an egg.” That’s why, for those with irregular periods, semiquantitative OPKs work best — or tests that allow you to measure your unique LH levels, rather than give you a positive or a negative result based on LH averages. This is how the Modern Fertility Ovulation Test works, which makes it a great option for people with irregular cycles.

Do you need to talk to your doctor if you’re trying to get pregnant and have irregular periods?

Like we mentioned earlier, it’s generally a good idea to check in with your doctor no matter what your reproductive goals are if your cycles are shorter or longer than 21-35 days, or if your periods are shorter or longer than 2-7 days. It’s also important to schedule a visit with your doctor if you experience any sudden changes, spotting, unusually heavy or long bouts of bleeding, extremely painful periods, or no period for three months.

But if you’ve recently gone off hormonal birth control so you can start trying to conceive, depending on your contraceptive of choice, it could take several months for your periods to return or regulate after stopping. So when should you make an appointment?

“If you’ve stopped your birth control and your period has not returned in 90 days or three months, then you’ll want to visit your healthcare provider,” Dr. Conti says. If your period did return after you got off birth control but it’s been 90 days since your last day of bleeding, that’s another reason to check in with your doctor.

When your period resumes after stopping birth control, it should follow the same cycle you had before hormonal medication. If the pattern of your periods has significantly changed and no longer fits into the standard parameters for a normal cycle, you should reach out to your provider for more insight. You may be experiencing anovulatory cycles, meaning you aren’t ovulating every month, or your birth control may have been “masking” polycystic ovary syndrome (PCOS) symptoms by managing your hormone levels and reducing any symptoms.

In any of these situations, your doctor can work with you to order blood work and potentially diagnose the cause of your irregular periods. (Your Modern Fertility Hormone Test results can help you kick these conversations off with your doctor.)

What fertility treatments can help when you have irregular periods?

If you talk to your doctor about medical assistance for getting pregnant with an irregular period, you’ll likely be prescribed medication to induce ovulation. “One of the best and most effective ways to get pregnant with an irregular period — or with a condition like PCOS — is medication like Letrozole or Clomid,” Dr. Conti says. “These treatments make you reliably ovulate every single month as if you had a normal period.”

While these medicines don’t erase the underlying problem, they help your body ovulate each month that you take them. The goal is to increase the rate of pregnancy to what it would be if your cycles were regular. Sometimes that’s all you need to help the sperm reach the egg and conceive. If not, treatments like in-vitro fertilization (IVF) and IUI can help increase your chances of getting pregnant.

Dr. Conti also recommends scheduling a preconception appointment before you actively begin trying to get pregnant so that you can prepare for what your fertility journey may entail. You can also ask any questions you may have about your cycle so that you know whether or not you’ll need to take some additional steps to conceive.

Most importantly, know that irregular periods do not mean that you’ll never get pregnant. You may have to track ovulation for a while or take certain medications, but, to quote Dr. Conti, it is “absolutely” possible to conceive. For more insight from Dr. Conti about irregular periods, watch the full live Q&A below — and stay tuned for more panels and info sessions with fertility experts.

This article was reviewed by Dr. Jennifer Conti, MD, MS, MSc.

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Rachel Sanoff

Rachel Sanoff is a writer and editor in Los Angeles. She was previously an essays editor at O.school, a digital sex education platform, and the features editor at HelloGiggles.

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