I Didn’t Know I Was Pregnant Period Every Month

The average age of menopause is 51. Anywhere from two to eight years before that, a woman experiences what’s known as perimenopause, a period when the body gradually produces less estrogen. During this time, it’s not uncommon to experience changes in your menstrual cycle — periods may come more or less frequently, be shorter or longer, or be lighter or heavier. But you’ll also likely experience hot flashes and night sweats, sleeping difficulties, vaginal dryness and mood swings. If you’re concerned about your symptoms, your doctor can check your hormone levels with a blood test.

Anovulatory Cycle: When You Don’t Release an Oocyte

When you’re trying to conceive, it’s normal to begin paying closer attention to your cycle. After all, in order to become pregnant, you first must ovulate.

It’s common to assume that your period is a sign that you’re ovulating normally. But surprisingly, that’s not always the case.

In an optimal scenario, a woman’s reproductive system will ovulate every month. But there can be situations that cause anovulation, or the lack of ovulation in a menstrual cycle. When that happens, you may still assume that the bleeding you’ve experienced was your monthly menstrual cycle. But if you’ve had an anovulatory cycle, it isn’t technically a period.

If you’re trying to get pregnant, it’s important to understand the causes of an anovulatory cycle and options for diagnosis and treatment.

As its name suggests, an anovulatory cycle occurs when a women skips ovulation. During ovulation, the ovary releases an egg, or oocyte.

It’s not uncommon for a woman in her prime conception years to experience an anovulatory cycle occasionally. In fact, you may have experienced one and not even noticed. That’s because when a woman experiences anovulation, she may still seem to menstruate normally.

In a normal cycle, the production of progesterone is stimulated by the release of an egg. It’s this hormone that helps a woman’s body maintain regular periods. But during an anovulatory cycle, an insufficient level of progesterone can lead to heavy bleeding. A woman may mistake this bleeding for a real period.

This kind of bleeding may also be caused by a buildup in the lining of the uterus, known as the endometrium, which can no longer sustain itself. It can be caused by a drop in estrogen as well.

A menstrual cycle without ovulation is most common in two distinct age groups:

  • Girls who’ve recently begun menstruating: In the year following a girl’s first period, known as menarche, she’s more likely to experience anovulatory cycles.
  • Women who are close to menopause: A woman between the ages of 40 and 50 is at a greater risk of changes to her hormones. This may lead to anovulatory cycles.

For women in both age groups, many changes are happening to their bodies. Sudden changes to hormone levels can trigger anovulatory cycles. Other causes include:

  • body weight that’s too high or too low
  • extreme exercise habits
  • eating habits
  • high levels of stress

If you’re having a period every 24 to 35 days, it’s likely that you’re ovulating normally.

In the United States, 10 to 18 percent of couples have trouble getting or staying pregnant. Chronic anovulation is a common reason for infertility.

Diagnosing an anovulatory cycle can be simple when a woman has no period, or periods that come very erratically. But that’s not the case for every woman.

To diagnose an anovulatory cycle, your doctor may check:

  • your progesterone levels
  • the lining of your uterus
  • your blood for the presence of certain antibodies

Your doctor may also perform an ultrasound to take a closer look at your uterus and ovaries.

The findings from these tests will help your doctor recommend the best treatment for you.

If these cycles are related to an outside influence like nutrition or lifestyle, effective treatments will include regulating eating habits and moderating physical activities. Making changes to your weight (gaining or losing weight as directed by your doctor) may also be enough to restart stalled ovulation.

Sometimes internal imbalances are the reason a woman is experiencing anovulatory cycles. In that case, your doctor may prescribe medications for fertility.

These medications are designed to combat the cause of a woman’s infertility. There are drugs designed to ripen the follicles, increase estrogen, and help the ovaries release an egg.

Surgery is an option in the event that a serious complication, such as a tumor, is discovered.

If you’re experiencing consistent anovulation — identified by very irregular and erratic cycles that vary wildly in length from one to the next — your doctor may recommend making small lifestyle changes.

Better nutrition, exercise, and stress relief can be very powerful. Try sticking to these changes for at least a few months, and then start paying close attention to whether your monthly cycle is becoming more consistent.

If these changes don’t seem to make a difference, or you just aren’t sure, speak to your doctor. Confirming the diagnosis of anovulation means you can find a solution.


Should you contact your doctor if you’re trying to get pregnant and are experiencing irregular periods?


If you have a history of irregular periods and are thinking of becoming pregnant, it may be a good idea to let your doctor know in case you experience difficulties conceiving. Sometimes irregular periods can be a sign that you may be at increased risk for infertility. Otherwise, if you’re over the age of 35 and have tried to conceive for six months, or under 35 and have been trying to conceive for 12 months, you should contact your doctor if you still haven’t become pregnant. If you have any questions or concerns, you can also feel free to contact your doctor.

Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Last medically reviewed on December 7, 2018

How we reviewed this article:

Healthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

  • Infertility FAQs. (2016).
  • Mayo Clinic Staff. (2014). Menorrhagia (heavy menstrual bleeding).
  • Mayo Clinic Staff. (2018). Female infertility.

Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.

11 Reasons for a Missed or Late Period

All What to Expect content that addresses health or safety is medically reviewed by a team of vetted health professionals. Our Medical Review Board includes OB/GYNs, pediatricians, infectious disease specialists, doulas, lactation counselors, endocrinologists, fertility specialists and more.

We believe you should always know the source of the information you’re reading. Learn more about our editorial and medical review policies.

Latest update:

Medically reviewed to ensure accuracy.

missed or late period causes

If your period shows up like clockwork each month, being even a few days late can make you wonder if you might be pregnant. These are the most common causes of a missed period, plus when to call a doctor.

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In This Article

  • Is it normal to miss a period?
  • Possible causes of a late or missed period
  • How late can your period be?
  • What to do when your period is late

If your period doesn’t make its monthly appearance, your first emotion may be joy if you’re trying to get pregnant. But while pregnancy is a common cause of a missed period, it’s not the only one: In fact, an irregular or skipped period happens to up to a quarter of all women of childbearing age.

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There are a number of reasons why your period may not show up on time — or at all. Missed-period culprits are often as simple as a shift in your schedule or a bout of illness. However, since an irregular or skipped period can also indicate a more serious underlying medical condition, such as thyroid disease or another hormonal imbalance, it’s smart to stay on top of it and, if it persists, get it checked out.

Is it normal to miss a period?

There are certain times when it’s not uncommon for your period to be irregular or not appear at all, including the first few years after menstruation starts, during pregnancy and while breastfeeding.

You may also skip a period at the end of your menstrual years as you approach menopause. During this time, it’s not unusual for your period to wax and wane, sometimes disappearing for months, until it stops completely. (You’re technically in menopause when you’ve gone over 12 months without a menstrual period.)

Possible causes of a late or missed period


Sometimes a late period means exactly what you think: You’re pregnant! Because many of the earliest pregnancy symptoms — including cramps, bloating, nausea, spotting, fatigue, breast tenderness and even food aversions — can be similar to what you may experience in the days before menstruation, it can be difficult to tell if your cycle is simply off by a few days or if you’re pregnant.

Read This Next

cramps but no period, pads on a blue background

PMS vs. pregnancy

happy couple in bed, early signs of pregnancy before a missed period

cramps but no period, pads on a blue background

PMS vs. pregnancy

happy couple in bed, early signs of pregnancy before a missed period

The fastest and easiest way to find out if pregnancy is the cause of your missed period is to take an at-home pregnancy test. These tests detect human chorionic gonadotropin (better known as hCG, a hormone released during pregnancy) in your urine. Pregnancy tests are most reliable the day after your missed period, but some brands claim to detect pregnancy up to five days before your period is due.


You already know that stress can trigger a number of unpleasant side effects, like headaches, weight gain and acne, so it should come as no surprise that it can also affect your menstrual cycle. When you’re under physical or emotional stress, your body produces the hormones adrenaline and cortisol. Elevated levels of these stress hormones force the brain to decide which bodily functions are essential and which are nonessential until the anxiety-inducing event is over.

Stress won’t typically cause problems with your cycle, but occasionally too much stress can lead to fluctuations in hormone levels, which could in turn mess with your body’s timing of ovulation and delay your period.


Certain illnesses, such as a cold or the flu, can also stress the body and impact ovulation, and, as a result, your period. If illness around the time of ovulation caused you to skip a period, it will likely reappear as normal next cycle.


Your weight can affect your hypothalamus, a gland in the brain responsible for regulating various processes in the body — including your menstrual cycle.

Extreme weight loss, low caloric intake or being very underweight can stress the hypothalamus. This could inhibit your body from producing the estrogen needed to build the lining of the uterus.

On the other hand, being overweight or gaining a lot of weight in a short amount of time can cause your body to produce too much estrogen. An overload may result in a few months without ovulation or cause the endometrial lining to overgrow and become unstable, resulting in heavy, irregular or missed periods.

Usually, consulting your doctor and gaining a healthy amount of weight if you’re underweight or losing if you’re overweight should help your periods to return to normal.

Excessive exercise

Of course, working out is good for you. However, when you overdo it (and possibly also restrict meals to lose weight), your body may not produce enough estrogen to complete the menstrual cycle.

Some women — such as ballet dancers, gymnasts and professional athletes — are at greater risk for amenorrhea (missing a period for three or more months in a row). But you don’t have to be a pro for exercise to mess with your system. Working out excessively without taking in enough calories can also cause disruptions.

Some possible signs that you’re overdoing it? Extreme or rapid weight loss, decreased physical performance, or forcing yourself to work out through injury, illness or severe weather. Slowing down a bit and gaining weight if needed should get things back on track.

Change in schedule

Believe it or not, switching things up — for instance, working the night shift instead of the day, or traveling across the country — can throw off your internal body clock, which helps regulate your hormones. Sometimes this results in a missed or late period, but it should return when your body gets used to the change or your schedule goes back to normal.


If you’re breastfeeding, you may not get your period for some time, since prolactin — the hormone responsible for breast milk production — also suppresses ovulation.

Many moms don’t have a period for months (or at all) while breastfeeding. But a lapse in your cycle doesn’t mean you can’t get pregnant. Remember, ovulation occurs before you get your period. It’s possible for you to ovulate and then get pregnant before you ever see your period.

Most moms should see their periods return within six to eight weeks after weaning. If you haven’t gotten your period three months after you stop breastfeeding, talk to your doctor.


Probably the most common medication to cause menstrual changes is birth control. Hormonal contraceptives such as the pill or patch work by stopping the body from ovulating — and no ovulation means no period. But what about that monthly bleeding you have while using one of these methods? What you’re really experiencing is withdrawal bleeding, a “fake” period caused by the drop in hormones when you take the placebo pills in your pack or go patch-free during the fourth week of your cycle.

Sometimes, though, birth control suppresses hormones so much that you have very light bleeding or no period at all during that week off. And some pills are even designed to stop your period for a longer amount of time (three months or more). Other hormonal birth controls, such as the Depo-Provera shot or the IUD, thin the lining of the uterus to such a degree that there may be no lining to shed monthly.

Emergency contraception, or the morning after pill, can also affect when or if you ovulate, so if you’ve taken it recently you may experience a late or skipped period. (Bring this up with your doctor.)

Some other medications that can cause your period to be irregular include antidepressants, some antipsychotics, corticosteroids and chemotherapy drugs.

If you’ve recently gone off the pill in the hopes of getting pregnant, you may notice that it takes a month or so for your cycle to regulate itself — in which case a skipped period might just be your system getting back on track. If you’re not sure whether you might be pregnant, however, visit your doctor.

Hormonal imbalance

Polycystic ovary syndrome (PCOS) is a condition where the female sex hormones are out of balance. PCOS can cause cysts on the ovaries and prevent ovulation from occurring regularly. In addition to missed or irregular periods, PCOS can also contribute to excess hair growth, acne, weight gain and possibly infertility. Trusted Source American College of Obstetricians and Gynecologists Polycystic Ovary Syndrome (PCOS) See All Sources [1]

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Your doctor can do a blood test to check your hormone levels if you think PCOS may be the reason for your menstruation problems. If PCOS is the cause, your doctor may recommend birth control to regulate your periods.

Thyroid disorder

When the thyroid, the gland responsible for your body’s metabolism, doesn’t function properly, it can cause abnormal menstrual changes. An overactive thyroid (hyperthyroidism) can cause periods to be lighter and less frequent. Additional symptoms include weight loss, rapid heartbeat, increased sweating and trouble sleeping.

An underactive thyroid (hypothyroidism) may also cause periods to be less frequent but heavier. Hypothyroidism can also cause weight gain, fatigue, dry skin and hair loss. Trusted Source American Society for Reproductive Medicine Hypothyroidism and Pregnancy: What Should I Know? See All Sources [2] A blood test can help your doctor determine if you have a thyroid disorder.


The average age of menopause is 51. Anywhere from two to eight years before that, a woman experiences what’s known as perimenopause, a period when the body gradually produces less estrogen. During this time, it’s not uncommon to experience changes in your menstrual cycle — periods may come more or less frequently, be shorter or longer, or be lighter or heavier. But you’ll also likely experience hot flashes and night sweats, sleeping difficulties, vaginal dryness and mood swings. If you’re concerned about your symptoms, your doctor can check your hormone levels with a blood test.

Though a missed period can be emotional, try not to jump to conclusions until you find out what’s really going on. A visit to your doctor can help pinpoint the cause, and if you’re not pregnant, coax your next period along and get things back to normal.

How late can a period be?

A typical menstrual cycle lasts 28 days, but depending on the woman, a healthy cycle can be as short as 21 or as long as 35 days. Trusted Source Mayo Clinic Menstrual Cycle: What’s Normal, What’s Not See All Sources [3] Track your period over several months to look for cycle patterns and changes. (There are some smartphone apps that make tracking easier.) This will help you figure out what a “normal” menstrual cycle usually looks like for you.

A period is usually considered late if it hasn’t started within seven days of when you expect it. Most pregnancy tests will also be able to give you accurate results by this time.

What to do when your period is late

If your period is more than a week late and you got a negative pregnancy test, you may want to check in with your health care provider to be safe.

If your practitioner rules out any other possible concerns, it’s fine to sit back and go with the flow (pardon the pun). Every woman skips a period now and then, especially if she’s under stress or has been sick. Relax and do what you can to ease anxiety by eating right, getting enough sleep and exercising.

But if you go more than 90 days without a period, or you miss a period more than three times a year, your doctor should do more in-depth testing to rule out an underlying medical condition.

From the What to Expect editorial team and Heidi Murkoff, author of What to Expect When You’re Expecting. What to Expect follows strict reporting guidelines and uses only credible sources, such as peer-reviewed studies, academic research institutions and highly respected health organizations. Learn how we keep our content accurate and up-to-date by reading our medical review and editorial policy.



  1. American College of Obstetricians and Gynecologists, Polycystic Ovary Syndrome (PCOS), January 2022. | Show in the article
  2. American Society for Reproductive Medicine, Hypothyroidism and Pregnancy: What Should I Know?, 2015. | Show in the article
  3. Mayo Clinic, Menstrual Cycle: What’s Normal, What’s Not, April 2021. | Show in the article
  4. What to Expect Before You’re Expecting, 2nd Edition, Heidi Murkoff.
  5. WhatToExpect.com, 14 Early Pregnancy Signs and Symptoms, July 2021.
  6. WhatToExpect.com, Irregular Periods and Getting Pregnant, August 2022.
  7. WhatToExpect.com, Breastfeeding: Basics and Tips for Nursing Your Baby, January 2022.
  8. WhatToExpect.com, HCG Levels During Pregnancy: What Is Normal?, May 2021.
  9. WhatToExpect.com, Pregnancy Tests, August 2022.
  10. WhatToExpect.com, PMS vs. Pregnancy Symptoms: Can You Tell the Difference?, September 2022.
  11. Mary Jane Minkin, M.D., Clinical Professor, Yale University School of Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, New Haven, CT.
  12. UptoDate, Evaluation and Management of Secondary Amenorrhea, April 2022.
  13. UptoDate, Patient Education: Absent or Irregular Periods, April 2021.
  14. American Society for Reproductive Medicine, Stress.
  15. American Society for Reproductive Medicine, Weight and Fertility, 2015.

Updates history

October 14, 2022

Editor: Caroline Picard

  • Minor copy and formatting changes.
  • Medically reviewed to ensure accuracy.

“I Didn’t Know I was Pregnant—Till Labor!”

“A woman feels a little ill. Not knowing why she’s queasy or has excruciating stomach pains, she calls for an ambulance. Shortly after it arrives, she gives birth — to a baby she never knew she was pregnant with,” reports the Connecticut Post.

These stories come up every now and then where women all over the world have no idea they are pregnant for three whole trimesters until to their surprise out comes a baby! I cannot understand at all how that is humanly possible. I know some women’s pregnancy symptoms aren’t as substantial as others, but I put on 20 pounds and looked like I swallowed a basketball—and padded my butt, and not in a bootylicious Kim Kardashian way. I had severe headaches, abdominal cramps, back pain, foot swelling, heartburn, morning sickness, bouts of alternating constipation, diarrhea and gas. I don’t know about you, but those symptoms weren’t an every day occurrence for me before getting pregnant. So if any of those things suddenly happened to me—and I hadn’t had a period in ages—I think I would have thought, “Hmm. something must be up. Time to get a pregnancy test!”

But that’s not at all what happened to Connecticut native Jennifer Scolin, who gave birth to her second child in an ambulance in her driveway. That’s right—her second child. After giving birth to her daughter Kelsey four years ago, Jennifer knew what it felt like to be pregnant. But she says this time around it was totally different. Her period was still regular until last month, and she felt totally fine until the day of her son Cole’s birth, when she woke up with sharp stomach pains. She called her husband to come home from work because she was feeling ill. Moments later, her water broke—that’s when the couple realized she was pregnant and called 911. She barely made it into the ambulance in time. In fact, two pushes and her 9 pound, 3 ounce son was out! Can you imagine? Most of us have pretty excruciating birth stories with hours and hours of labor involved. Two pushes and you have a baby? Unbelievable! And he was no little thing! Over nine pounds, and you didn’t realize you were pregnant? All I can say is wow!

The most shocking thing, though, is that this is the second story like this, this week! Across the pond in England, 20-year-old Sophie Aldridge went to the hospital complaining about back pain she chalked up to severe period cramps. According to The Daily Mail, the doctors sent her home with a dose of painkillers. Hours later she was back in the hospital—giving birth!

After the pains became increasingly strong, Sophie’s mom called an ambulance to take her back to the hospital. In the ambulance, her water broke and the medics realized she was pregnant. Sophie says her period kept coming, she didn’t put on any weight, and never had morning sickness so she was surprised (to say the least!) to give birth to a 5 pound, 8 ounce son, Thomas, just 30 minutes after entering the hospital the second time.

According to studies, undiagnosed pregnancies aren’t as rare as you’d think. One in 600 mothers-to-be report they didn’t realize they were pregnant until going into labor.

TELL US: Can you believe someone wouldn’t know they were pregnant until they went into labor? Has this happened to you or someone you know? Share the details!

Think you may be pregnant? Take our quiz to find out so you don’t get an unexpected surprise in nine months!

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Alex Koliada, PhD

Alex Koliada, PhD

Alex Koliada, PhD, is a well-known doctor. He is famous for his studies of ageing, genetics and other medical conditions. He works at the Institute of Food Biotechnology and Genomics NAS of Ukraine. His scientific researches are printed by the most reputable international magazines. Some of his works are: Differences in the gut Firmicutes to Bacteroidetes ratio across age groups in healthy Ukrainian population [BiomedCentral.com]; Mating status affects Drosophila lifespan, metabolism and antioxidant system [Science Direct]; Anise Hyssop Agastache foeniculum Increases Lifespan, Stress Resistance, and Metabolism by Affecting Free Radical Processes in Drosophila [Frontiersin].
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