Irregular Menstrual Cycles and Fertility
Finding the cause may help minimize the effect
Irregular menstrual cycles—defined as having cycles that are shorter than 21 days, longer than 35 days, or vary between extremes—are very common. Most women will have times when their periods get a little wacky due to illness, travel, or stress.
“Having the occasional irregular cycle is nothing to be concerned about,” says Dr. Corrine Kolka Welt, MD, a reproductive endocrinologist at Massachusetts General Hospital and an assistant professor at Harvard Medical School. Still, according to a study led by Dr. Karen Barnard, MD, MPH, an associate professor of clinical internal medicine at the University of South Carolina School of Medicine, about 17 percent of women report experiencing consistently irregular cycles, which may have an effect on fertility or indicate a health concern.
“I’ve been having irregular cycles since college,” said Ann Chavie of Chicago, Illinois, “I used to get my period every couple of weeks! Now, after being on the pill and then stopping to try to have a baby, I have really long cycles.”
“My cycles are all over the place,” said Ella Longoria [not her real name] of Denver, Colorado. She thought it was her demanding and erratic schedule as a resident physician that was making her cycles irregular. “But now that I’m an attending physician and I work regular hours, my cycles have not settled down,” she said.
According to Dr. Welt, there are three very common reasons why a woman might be having irregular cycles:
- Being too thin or exercising too much
- Polycystic ovary syndrome (PCOS), which indicates disruption in the hormonal balance and is characterized by excessive hair growth, acne, and irregular cycles
- Early menopause
Other culprits behind irregular cycles can include thyroid problems or high levels of the hormone prolactin (which is normally present at high levels only when a woman is breastfeeding).
The Ideal Cycle
The main concern with irregular cycles for women who want to conceive is that they might not be releasing a mature egg, or ovulating, during their cycles. Here’s a quick rundown from Dr. Welt on how the menstrual cycle works in a textbook 28-day cycle. The menstrual cycle is broken down into two phases. The first phase is called the follicular phase. It lasts about 14 days, from the first day of your period until the day of ovulation. During the follicular phase, three things happen:
- The egg follicle begins to mature in the ovary.
- The uterine lining thickens and becomes ready for a fertilized egg to implant.
- At day 14 of a textbook cycle, high levels of estrogen cause a surge of a hormone called luteinizing hormone, which triggers ovulation.
Following ovulation, the luteal phase begins. The luteal phase lasts for another 14 days, and is marked by high levels of progesterone and estradiol. These hormones keep the uterine lining ready for implantation. If no embryo implants, progesterone and estradiol levels fall and the uterine lining is shed through menstruation.
Menstruation Doesn’t Equal Ovulation
“I knew my cycles were irregular, but I figured that since I was still menstruating, I would go ahead and try to conceive and have a baby,” said Chavie. “It didn’t quite work out that way.”
Ovulation is key to conceiving. You can’t get pregnant without releasing an egg. Even if a woman has some periods, it doesn’t mean that she is ovulating. The body can still shed the uterine lining without ovulation occurring. In fact, according to Dr. Welt, a classic study from the 1960s found that women with cycles shorter than 21 days or longer than 35 days are much more likely not to be ovulating during their cycle.
Even if a woman with irregular cycles is still ovulating, fertility might be affected. If a woman’s cycle is very long, for example, lasting 40 or 50 days, it can be hard for a couple to figure out when the egg is released and when they should be having intercourse.
“We just had to go with my best guess when we were trying to conceive,” said Longoria. “And it wasn’t working!”
Tips for Women with Irregular Cycles
Dr. Welt recommends the following steps to increase your chances of conceiving:
- Keep track of your cycles and document their length
- Consider using your basal body temperature (BBT) to determine if you are ovulating
- Use a urine-based ovulation predictor kit (OPK) to help you determine if you are ovulating and when. Take the average length of your cycles and subtract 14 days to find your likely ovulation day. During the next cycle, begin using OPKs starting two days before the predicted ovulation day. (For example, an average cycle length of 35 days minus 14 equals 21. Begin using your kits on the nineteenth day of your next cycle.)
“The ovulation predictor kit was key for us,” said Longoria. “We got pregnant the first month that we began using a digital, urine-based testing system at home.”
Some women, like Longoria, are able to work around their irregular cycles by keeping track and using OPKs, but that’s not always the case. If you cannot determine whether you are ovulating, if you are concerned about PCOS or other medical problems, or if you have been trying to conceive for several months without success, make an appointment to see your gynecologist or a reproductive endocrinologist. Using ultrasound and blood tests, the doctor will be able to determine if you are ovulating regularly and can get to the root of the irregular cycles. Luckily, there are ovulation-induction treatments available for women who do not ovulate and for women with PCOS.
That’s the route that Chavie had to take. “I had a bunch of tests done by a reproductive endocrinologist,” she said. “It seems to be a combination of thyroid problems and PCOS that’s causing me not to ovulate and to have irregular cycles. I’m taking some medications, which are helping.”
In conjunction with traditional medical treatments, some women with irregular cycles choose to pursue alternative medicine, such as acupuncture. Because there are no clinical trials proving the benefit of alternative medicine, Dr. Welt does not advise it. “There are some women who are very stressed, whose stress is affecting their cycles. These women may benefit from the calming effects of alternative medicine,” says Dr. Welt. “But in general, if a woman isn’t ovulating, it’s because of a medical problem, and I wouldn’t recommend alternative medicine to treat that.” Chavie did find acupuncture helpful for her, though. She realized that using acupuncture along with her medications produced the best results. “I can ovulate on my own when I do both those things,” she said. “We’re still trying, but we’re hopeful.”
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