As much as we typically dread the arrival of Aunt Flo and all the pesky side effects that come along with her, most of us become slightly alarmed when she’s late. While it’s not always a sign for concern, there are some reasons for a missed period that are more alarming than others. “There are many reasons why a woman may miss her period, including lifestyle factors such as stress and diet,” explains Israel Carmona, MD, fertility expert at Institut Marques. “However, a missed period can also signal more serious implications, including pregnancy and underlying medical conditions.”
If you get your period, just not regularly or within the 28- to 35-day window that is deemed “normal” in the medical world, don’t freak out just yet. Almost every woman has an irregular cycle at one point in her life, and as many as 20 percent of women get this on a regular basis, according to Philip Chenette, MD, a member of Progyny’s Medical Advisory Board. If you’re dealing with a missed period or irregular periods on a consistent basis, here are a few possible reasons why.
Of course, the most common reason for a missed period is pregnancy. “If you are sexually active, this is a possibility — even if you are on contraception, it is not always 100 percent effective,” says Dr. Carmona. “A missed period is the most reliable sign of pregnancy, but it’s also important to note some women who are pregnant can still experience light bleeding at the time their period would be due.” This light bleeding is typically referred to as “implantation bleeding,” signaling that the egg has officially been fertilized by the sperm.
The second most common reason for a missed period is no or low hormones, which could be a sign you have polycystic ovary syndrome (PCOS), a hormonal disorder that can impact up to 1 in 5 women. “PCOS causes a hormonal imbalance that can impact the menstrual cycle or even cause it to stop,” explains Dr. Carmona. “The condition can also have other side effects such as weight gain and excess hair growth.” If you think you may be suffering, he recommends speaking to your OBGYN immediately, as it can have a longer-term impact on fertility.
Certain forms of birth control, such as an IUD, the progestogen-only pill, contraceptive injections like the Depo-Provera shot, implants or the coil can have an impact on your period, causing them to become irregular, lighter, or non-existent, explains Dr. Carmona. “It is important to find out what works for you, as some women find that contraception has a positive impact on their cycle and others find it worsens it,” he adds.
Going off birth control
If you’ve been on birth control for several years, or even decades, it’s not uncommon to experience delayed cycles once you finally decide to stop. “It can take time for the pituitary to wake up after being repressed for so long, plus hormone-containing IUDs and certain birth control pills can create an atrophic endometrium in the uterus that prevents the endometrium from responding to hormones of ovulation,” says Dr. Chenette. “There are a variety of other medications that can affect menstrual cycles, such as chemotherapy and antidepressants.”
Extreme weight loss
If you’ve recently lost a significant amount of weight, either through dieting or exercising, your period may be affected. As a result of such extreme dieting or exercising (this is common in gymnasts, for example), missed periods may occur, notes Lakeisha Richardson, MD, an OBGYN in Greenville, MO. In addition, she points out that women who are underweight in general are more likely to have missed periods. “The percentage of body fat in these women plays a major role in regulating the menstrual cycle.”
Extreme weight gain
On the contrary, being overweight or obese can also lead to a missed period. “Being overweight can cause the body to produce an excess amount of oestrogen, which may cause a hormonal imbalance and subsequent missed period,” explains Dr. Carmona. If your weight is beginning to impact your menstrual cycle, he recommends scheduling a visit with your general practitioner for advice on how to safely lose weight.
“The thyroid hormone plays a significant role in many metabolic actions in the body, including having regular periods,” explains Anate Brauer, MD, a reproductive endocrinologist at the Greenwich Fertility and IVF Centers and assistant professor of OBGYN at NYU School of Medicine Having. “An over- or underactive thyroid may send signals to the brain to stop making hormones necessary to induce normal ovulation and menses.”
Physical or emotional stress
As you know, stress can have an impact on more than just your mind. In fact, it’s one of the major culprits for a missed period. “Stress can affect the part of the brain responsible for producing hormones, and this change in hormone levels can alter the frequency and duration of the menstrual cycle — or make it stop altogether,” says Dr. Carmona. “Reducing stress levels through coping mechanisms such as breathing exercises and physical activity may help your body revert to a normal period.”
There are genetic explanations for missed periods, such as Turner Syndrome and Swyer Syndrome. Both of these conditions are congenital, meaning the individual is born with it, explains Dr. Chenette. “These conditions may be discovered in early teen years, typically in a teen with monthly pelvic pain, but no menstrual flow.”
Of course, when a woman runs out of eggs to ovulate with, aka menopause, which typically occurs around the age of 51, she will no longer experience a period. “The hormonal changes involved in the build up to menopause can indeed cause missed periods,” explains Dr. Carmona. “Estrogen levels will start to decrease, and ovulation will gradually become less regular.” While menopause is a natural part of the female aging process and is nothing to be concerned about, women can occasionally run out of eggs too early, during their reproductive years — a condition known as premature ovarian insufficiency (POI),” explains Dr. Chenette. If you think you might be experiencing menopause at an early age, schedule a visit to your OBGYN.
While these are some common reasons for a missed period, it's always recommended to contact your OBGYN if anything feels off. You know your body best -- trust your instincts.