Why do I have a late period if I’m not pregnant? Possible explanations

Whether you’re used to a little variation or your cycle runs like clockwork each month, a late or no-show period can be confusing. Since a missed period is one of the earliest signs of pregnancy, you may take a test to confirm this. You can use Flo’s pregnancy test calculator to determine the best time to take a test to get an accurate result. 

If you get a negative result, it can feel doubly confusing. However, pregnancy isn’t the only reason why your period might be late. In fact, hormonal changes, birth control, and stress can all have a bearing on your cycle. 

Here, a Flo expert will cover why you might have a late period but not be pregnant. 

Key takeaways

• If you’ve had a late or missed period, your first resort can be to take a pregnancy test. If you think there could be even the smallest possibility that you could be pregnant, then it’s good to rule it out with a test.
• If your test comes back negative, but your period doesn’t show up, then it’s important to investigate the other possibilities. 
• It’s very typical for your cycle to change over your lifetime. Your hormones go through natural fluctuations, which can make your cycle irregular. 
• A late or missed period can also be caused by changes to your lifestyle, or it may be a sign of an underlying health condition. 
• Speak to your doctor if you are having late, missed, or irregular periods. They will be able to walk you through your symptoms and determine the best next steps. 
• You can also log your period using an app like Flo. This may help you spot patterns to bring to your doctor. 

7 possible reasons your period could be late other than pregnancy

Noticing a change in your cycle can be frustrating, but it’s actually pretty typical for your cycle to vary slightly. “Some people have cycles almost the same length every time, while some people have variable cycles,” says Dr. Jenna Flanagan, an assistant professor of obstetrics and gynecology at the University of Utah, US, and member of Flo’s medical expert board. “Therefore, if one month, your cycle was 25 days, and your next cycle was 32 days, that would not be considered pathologically late. Instead, it would just be within the normal range of menstrual cycle length and timing.”

You can log your period using an app like Flo to build a better understanding of how long your cycles typically are. If yours are shorter or longer than 21 to 35 days, or if you miss your period altogether, there are a number of reasons why this could be the case.

1. Stress

We might feel stress emotionally, but it can also have a huge impact on our physical health, including our cycles. 

“Anything that stresses the body, including physical illness, immune system, or psychologically, can cause the body to delay or skip ovulation for a cycle as a self-protection mechanism,” says Dr. Flanagan. “So, the body senses this stress and understands that pregnancy timing now would not be ideal.” 

When you’re stressed, your body releases the hormone cortisol. It does this to protect you as cortisol is what sends you into “fight-or-flight” mode. However, cortisol can disrupt the normal functioning of your cycle hormones. This could temporarily stop your period. 

We’re all different, and often, finding stress management techniques that work for you starts with identifying the cause of your stress. You might find it helpful to:

• Speak to a mental health expert.
• Spend some time each day moving your body if you can. 
• Catch up with a friend.
• Allow yourself the space to do activities that bring you peace of mind. 

2. Changes in weight

If you’ve lost or gained a significant amount of weight in a short space of time, this can impact your periods. For example, losing weight suddenly can cause your metabolism to slow. Your body may temporarily stop your periods as its way of telling you it doesn’t have enough resources to support a possible pregnancy. 

Gaining a significant amount of weight can also impact hormone levels. As we’ve already mentioned, fluctuations in your hormones can impact your menstrual cycle and the timings of your periods.

Weight changes can be an incredibly sensitive and personal topic. If you think that your irregular periods may be due to a change in your weight, don’t hesitate to speak to your doctor. 

3. Birth control

Hormonal birth control can also be responsible for changes in your cycle. This is because it can impact or prevent ovulation (the point in your cycle when one of your ovaries releases an egg). 

Some types of hormonal contraception, such as the progestogen-only pill, contraceptive injection, and intrauterine system, can cause periods to stop completely while you’re using them or can cause irregular bleeding. It’s also worth noting that the length of time it takes for your period to return after stopping birth control will depend on the type you were using. 

If you’re picking a new type of birth control or have questions about the option you’re currently using, it’s always best to consult your doctor. They will be able to outline the pros and cons of each choice. 

4. Perimenopause

Perimenopause describes your transition to menopause, which you’ll know you’ve reached when you haven’t had a period for 12 months. It can start any time between your late 30s and your 50s. For most people, perimenopause will last somewhere between four to eight years. 

During this time, your hormone production begins to change. In particular, the levels of estrogen produced by your ovaries start to fluctuate, meaning that they could go up and down. It’s this erratic estrogen production that can cause the symptoms linked to perimenopause, such as changes to your cycle, mood swings, and brain fog. 

“During perimenopause, the secretion of hormones from your ovaries is affected, namely the estrogen secretion,” explains Dr. Flanagan. “It becomes more dysregulated, and the ovaries may not produce an egg every cycle or may ovulate late due to hormonal changes, which can affect the timing, quality, and characteristics of the menstrual cycle.”

You can learn all about the signs and symptoms associated with perimenopause using Flo. 

Perimenopause is something that all of us will experience, but your doctor is there to guide you through any new symptoms and support you. 

5. Thyroid problems

At the base of your neck, there is a butterfly-shaped gland known as your thyroid gland. This gland is important because one of its main functions is to release hormones that regulate the body’s metabolism — how your body turns food and drink into energy. 

If your thyroid gland produces too many hormones, it’s known as overactive (hyperthyroidism), or if it doesn’t make enough, it’s known as underactive (hypothyroidism). Either of these conditions can cause you to have irregular or missed periods.

If you speak to your doctor about your irregular cycles, they may test how your thyroid is functioning to rule out hyperthyroidism and hypothyroidism.

6. Primary ovarian insufficiency (POI)

Primary ovarian insufficiency describes when your ovaries stop working as they normally would before you reach the age of 40, leading a person to go through early menopause. It causes your estrogen levels to drop, which can mean your cycle becomes very irregular and can even stop entirely. POI is rare, however, as only about 1% of women under 44 experience POI. 

If you miss a period, it’s important not to self-diagnose, and, as we’ve said, POI is quite a rare diagnosis. Speak to your doctor about the possible causes if you’re concerned. 

7. Polycystic ovary syndrome (PCOS)

PCOS is a condition that can cause irregular periods. Around 8% to 13% of reproductive-aged women have PCOS. It causes the body to produce a higher amount of androgen hormones, which can prevent an egg from being released (ovulation), leading to delayed or missed periods. 

While it isn’t the same for everyone, typically, symptoms start to show in your late teens and early twenties and can include: 

• Irregular periods or no periods at all
• Excessive hair growth, often on the face, back, chest, and bottom 
• Weight gain
• Acne or oily skin
• Hair loss from the head
• Difficulties getting pregnant

If you think you may have PCOS, speak to your doctor as that’s the only way to know for sure. A combination of lifestyle changes and medication can often be used to effectively manage PCOS and its symptoms. Want to learn more about PCOS? Take our quiz. 

Consult a trusted medical professional about irregular periods

If you know for sure that you aren’t pregnant, but your period is late or hasn’t shown up at all, then speak to a health care professional. There are lots of reasons why this may happen, and they will be able to help you figure out what’s going on. 

Similarly, you can log your periods and cycle symptoms using an app like Flo. This may help you spot patterns, and you can show your app to your doctor during your appointment to help you explain what’s going on.