If it’s always a bit of a mystery when your period is going to show up—perhaps your cycle is 35 days some months and 21 days others—you might find getting pregnant more challenging because you never know when you’re ovulating. So what’s going on down there? Here’s what you need to know about your irregular periods.
Let’s start by defining what an irregular period actually is. You don’t need a 28-day cycle to be regular. “Only about 15 percent of women have a 28-day cycle,” says George Carson, a Regina-based OB/GYN. In fact, the normal length of a cycle can vary between 22 to 35 days. So, as long as your cycle falls within that window and runs about the same length each time, it’s regular.
But, if you can’t count your cycle and pinpoint within a day or two when your next period will come, you may be irregular. While there are conditions that can affect the regularity of your period—including stress, thyroid conditions, polycystic ovary syndrome (PCOS), fibroids and more—even if your irregular cycle isn’t the result of a health condition, it can affect your fertility.
No matter the length of her period, every woman ovulates about 14 days before her next period. So, if you have a 28-day cycle, you’ll ovulate on day 14, and if you have a 32-day cycle, you’ll ovulate on day 18. But, when you have an irregular cycle, identifying an ovulation date isn’t so easy, because without knowing when you’re going to get your period, you don’t know when to count back 14 days from.
Women with irregular periods are also more likely to be anovulatory, which means they simply don’t ovulate. They may bleed on occasion, but the menstruation isn’t following the release of an egg. Carson says women experiencing anovulation likely won’t feel typical period pains, such as cramping, and their periods can be light or heavy in flow.
Some women ovulate occasionally but it’s irregular and unpredictable, which can also make it a challenge to conceive. “A woman ovulating with a 28-day cycle ovulates 13 times a year. So there are 13 times in which she can get pregnant and she can figure out when they are,” says Carson. “But if she ovulates six times a year, right away it’s half as likely that she’ll get pregnant.” And being irregular will make it a challenge to even track down those six times when you’re actually fertile.
While women with regular cycles can simply assume they’re ovulating at the same time each month, it’s a bit trickier for those with irregular periods. Fortunately, there are a few ways to figure out your body’s schedule.
The first sign to look for is mucus. “If you get a lot of clear, sticky mucus in the middle of your menstrual cycle, then you’re probably ovulating,” says Beth Taylor, an OB/GYN with the Vancouver-based Olive Fertility Centre. The mucus, which is secreted thanks to an increase in estrogen, means your cervix is ready to be penetrated by sperm to get pregnant.
Another way to determine if you’re ovulating at all is to track your temperature each morning with a basal body temperature thermometer, which can hone in on small changes up to 1/100th of a degree. After the egg is released in your body, both estrogen and progesterone are flowing. The progesterone causes your body’s temperature to increase by half a degree Celsius (or a full degree Fahrenheit).
But this method is a bit tricky for women with irregular cycles. Because the temperature change indicates the egg has already released, it means you need to have sex just before the increase in order to hit your fertile window. Most women track their temperature and use the data to predict when it’s going to rise in future months. But even if your cycle is a little unpredictable, “It can be useful in looking backwards to see: am I likely to ovulate? And when?” says Carson.
You can also use ovulation predictor kits that test your urine to figure out when to have sex. Before ovulation, women produce a surge of luteinizing hormones (LH), which triggers the drop of an egg from the ovary. “When a strip indicates an LH surge, she’s going to ovulate that day or the next day and she can use this information to time intercourse,” says Carson.
“If you’re trying to get pregnant and your periods are irregular, talk to your doctor about it right away,” says Taylor. To help things along, bring in three months of your tracked basal body temperature. This can help your physician diagnose whether you’re not ovulating or see if you need help regulating your ovulation schedule. There are some medications available to induce ovulation, including letrozole or clomiphene. Your doctor may also look for signs of other conditions, like PCOS, that could be leading the the irregular periods. Either way, Carson says, “There are effective treatments available.”