9 Potential Reasons You Missed Your Period

You're Stressed

Stress (physical and mental) is a common reason why someone might miss their period. “Big life events can cause a missed period as well, for likely the same physiological reasons as stress," says Twogood. "An example is a big vacation. We don’t think of that as stressful, but changes in daily activities, irregular sleep, and circadian rhythm all come into play." Perhaps you’re just stressed from a big project or a big move, you’ve been sleeping very poorly, or maybe you’re just recovering from jet lag after a short vacation.

Dweck also mentions that UTIs might not directly cause a missed period, but the stress and discomfort of a UTI can also exacerbate a delayed period.

You've Had Sudden Changes in Your Weight

Twogood also says that significant and sudden changes in weight can cause someone to miss their period. “Both weight gain and weight loss,” she says, can be reasons why a period is missed. Going too far in either direction can just be physically jarring for a body, and these sudden changes can prevent the body from having a normal period. A detox diet, a new vigorous workout routine, or going from very active to sedentary can all be factors.

Polycystic Ovarian Syndrome (PCOS)

Polycystic ovarian syndrome, or PCOS, is a very common hormone disorder. Those with PCOS produce more androgen than usual for a body with female reproductive organs, which can cause ovarian cysts. PCOS can also cause irregular periods, says Twogood. Without enough of the correct hormones to trigger ovulation, it would not be possible to menstruate.

Hormones

According to Twogood, a high prolactin level can also cause you to miss a period. Prolactin is a hormone that is known to stimulate the production of breast milk. High prolactin levels can get in the way of a normal production of estrogen and progesterone, which can throw your ovulation and menstruation cycles off.

You Have a Thyroid Disorder

Your thyroid plays an important part in your menstrual and reproductive health. If you can’t recall the details of your high school biology class, your thyroid is a gland that produces and releases hormones, and it interacts with your reproductive system to keep your ovulation and menstruation running on time. This means that whenever the thyroid is not working properly, your ovulation and menstruation can both be impacted, leading to missed or irregular periods. This can happen with both hypothyroidism and hyperthyroidism.

You Experienced a Biochemical Pregnancy

This might seem like an obvious reason why someone might miss their period, but it isn’t just a normal pregnancy that can cause a missed period. Twogood says that something like a biochemical pregnancy (which is basically a miscarriage very, very early in the first trimester) can cause a missed period, and the elevated levels of hCG in your blood can cause a positive pregnancy test. But, depending on the levels of hCG in your body at the time of the miscarriage, your body may take longer to start menstruating again normally. The more hCG, the longer it will take. This can mean that you might miss a period as your body re-regulates itself.

You Just Used Emergency Contraception

It might seem a little strange that an emergency contraceptive could cause a missed period, but it’s totally normal according to Twogood. An emergency contraceptive, like Plan B, contains the progestin hormone levonorgestrel, which is also in hormonal birth control. Levonorgestrel prevents ovulation, which can cause menstrual abnormalities. The high concentration of levonorgestrel in emergency contraceptives can alter your body’s natural hormonal cycles, which can lead to a delayed or missed period.

You're On an Antidepressant

This one might be surprising, but Twogood says that “some medications, like anti-depressants, have been reported to cause some initial changes in periods, too. This may be linked to a change in weight experienced with SSRIs (selective serotonin uptake inhibitors) and/or SNRIs (serotonin and norepinephrine reuptake inhibitors) or from the mental health component, not just the medication itself."

No Reason at All

Maybe none of the above apply to you. You’re not stressed, have not made any significant lifestyle changes, your weight is unchanged, you’re not on birth control or any medications, and you don’t have any other conditions that could have an effect on your cycle. That’s totally normal as well.

“Sometimes, we can’t find an explanation as to why someone missed their period,” says Twogood. Again, this is also normal, but if it becomes a recurring phenomenon, you might want to consider using a period tracking app to help you accurately track your symptoms and the length of your cycle. It’s possible that your cycle is longer than most others, but is still regular.