What a Short Menstrual Cycle Says About Your Pregnancy Odds

Have a 26-day cycle? Or even 24? While short menstrual cycles don't always impact fertility, in some case, they do. Here's what to know.

Preparing Girls for First Period: Menstruation supplies
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Having a menstrual cycle that's on the shorter side is actually quite common—the normal range can be as short as 21 days and as long as 35 days! Still, if your cycle is short, or irregular, you might be concerned about how this could impact your fertility.

Although shorter cycles don't always impact fertility, having concerns about your cycle length is totally understandable. We reached out to experts to explain how short menstrual cycles could affect fertility, what you can do to address any issues, and how you can optimize your chances of conception if you have a shorter cycle.

What Is a Menstrual Cycle?

A menstrual cycle refers to the monthly shedding of your uterine lining. Each month, your uterus builds up this lining—composed of blood and uterine tissue—in preparation for a possible pregnancy. But if this doesn't occur, you shed the lining, which results in you getting your period.

Most people who menstruate have a cycle between 21 and 35 days, with the average cycle being about 28 days long. Menstrual cycles are usually divided into four parts:

  • The menstrual phase, where you bleed—usually for about three to five days
  • The follicular phase, where your body gets ready to release an egg
  • The ovulatory phase, where your body releases an egg—this usually happens about 14 days into your cycle
  • The luteal phase, where your body prepares the uterus for pregnancy—this usually lasts about 14 days

Although it's normal for menstrual cycles to vary from one person to another, having very short, very long, or unusually erratic cycles can be a sign of fertility concerns, says Jenna Turocy, MD, OB-GYN and reproductive endocrinologist at Columbia University Fertility Center. "Menstrual cycle reflects a person's overall health status and should be thought of as a key vital sign," she explains. "Variations in the length of the menstrual cycle may indicate hormonal imbalances and whether or not ovulation is occurring in a predictable manner."

How Does a Short Menstrual Cycle Affect Fertility?

It's important to note that having a short cycle in and of itself doesn't mean you will have trouble getting pregnant. "Some variation in cycle length can be normal," explains Michael Zinger MD, reproductive endocrinologist at RMA Long Island IVF. However, if you usually have a cycle that's less than 26 days, something may be amiss.

There are two main things that can go wrong in a shorter cycle that can impact fertility, Dr. Zinger explains. First of all, if your cycle is short, it may indicate that you are having trouble ovulating or that ovulation isn't occurring. Another issue that a short menstrual cycle could indicate is that your luteal phase (the period between ovulation and menstruation, when your uterine lining is building) isn't long enough.

So how do you know whether there may be an issue? "The easiest way to tell which of the phases is shortened is to track ovulation, which can usually be done with over-the-counter urine tests," says Dr. Zinger. "Most urine tests for ovulation will turn positive a day or two before ovulation, so that should be about day 12 of the cycle, with ovulation then happening about day 14." If ovulation seems to be occurring earlier than that, it may indicate that your follicular phase is short.

A shorter follicular phase isn't always a problem, as long as you are ovulating. But if you are older and experiencing a shorter follicular phase, it's something to talk to your healthcare provider about. "If the follicular phase has become shorter with age, it may be an indication that the egg supply is decreasing," Dr. Zinger says.

Alternatively, if ovulation is occurring about halfway through your cycle, but then your next period occurs less than 10 days later, you may have a short luteal phase. According to the American Society for Reproductive Medicine, luteal phases that are less than about 10 days might indicate a luteal phase defect, which can impact fertility. Even if you ovulate, if your body isn't able to secrete the hormones (primarily progesterone) to support pregnancy during the luteal phase, and build up a proper uterine lining, pregnancy may not be successful.

If luteal phase defects are suspected, your healthcare provider will carry out certain tests to figure out what is causing this issue, says Dr. Zinger. "A doctor can check for hormone conditions that are causing luteal phase defect, such as a thyroid disorder or over-production of prolactin hormone," he explains. "Fixing these underlying conditions with the correct medication would then also correct the luteal phase defect."

Increasing Your Chances of Conception When You Have a Short Cycle

If you are concerned that your short menstrual cycle is impacting fertility, there are two main areas to focus on: identifying/treating any medical conditions that can affect fertility, and becoming more aware of the signs of ovulation. Let's take a look at each of these.

Treat any underlying medical conditions

There are a few main medical issues that may be related to short menstrual cycles and that can impact fertility, says Dr. Turocy. "If you are concerned, and your menstrual cycle is short, work with your doctor to try to determine the cause," she recommends. Shortened cycles can be a sign of several medical issues, including:

  • Ovarian aging, or decreased ovarian reserve
  • Thyroid dysfunction
  • High prolactin
  • Short luteal phase

For each of these conditions, there are effective treatment options, and hope for future conception. For example, thyroid issues can be addressed by thyroid medications to help your body reach appropriate levels. Likewise, high levels of prolactin can be remedied with medication, and addressing any physiological issues that may be causing the problem.

Luteal phase defect is usually addressed with hormonal medication or medication to stimulate ovulation. Finally, if you are dealing with decreased ovarian reserve, there are options to maximize your chances of conceiving, such as using IVF, freezing your eggs for later use, or using a donor egg.

Learn the signs of ovulation

If you are ovulating, timing sex around ovulation can increase your chances of conceiving, and learning the signs of ovulation is a smart idea—whether you are having fertility issues or not. "Knowing when you ovulate can help you figure out when you're most fertile and the best time to have sex," says Dr. Turocy. "I recommend having sex every one to two days during your fertile window (6 days before ovulation)."

How can you tell when you are ovulating? Thankfully, there are actually quite a few signs:

  • More copious, slippery cervical fluid (with egg white consistency)
  • Increased sex drive
  • Bloating
  • Pelvic pain, usually on one side
  • Spotting or light bleeding

Using a calendar to track your cycle can help you know when to start looking for signs—usually about two weeks after day one of your period. Other methods include other-the-counter ovulation detection kits and using basal body morning temperature readings. Body temperature rises slightly after ovulation, and tracking your temperature can help you get more in tune with when you are ovulating and what the signs look like in your body.

What Else to Know About Fertility for People With Short Cycles

Probably the most important thing to keep in mind about trying to conceive with a shorter menstrual cycle is that you shouldn't shy away from seeking help. "If your menstrual cycles are irregular— your period comes more frequently than every 21 days or you go more than 35 days—you don't need to wait a certain amount of time before seeing a fertility specialist," says Dr. Turocy. "Working with a fertility specialist right away to help determine the cause of the irregular cycles can help increase your chances of getting pregnant."

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