Long Menstrual Cycles? What You Should Know

Do you wait longer than other women for your period to show up each month? If so, you might be experiencing long menstrual cycles. While the average menstrual cycle is 28 days, normal menstrual cycles can range anywhere from 24 to 38 days in adults. Teens may have to wait even longer between menses, but they should start experiencing normal menstrual cycles within three years of their first period.

The menstrual cycle is counted from the first day of one period to the first day of your next period, with most women experiencing menstrual flow for two to seven days. Your monthly cycle is controlled by the rise and fall of hormonal levels. If you’re unsure of just how long your menstrual cycle lasts, there are a number of amazing apps out there. They can help you track the timing of factors like ovulation, bleeding, and any symptoms tied to your cycle.

Why Is My Menstrual Cycle So Long?

Your menstrual cycle is considered long if it lasts more than 35 days. If you don’t have a period for more than 90 days, you can be diagnosed with infrequent menstruation – also called oligomenorrhea.

There are many factors that could cause a long menstrual cycle. Some of the most obvious include pregnancy and perimenopause (a pre-menopausal state that occurs when women get into their late-30s or 40s). Here are a few more of the most common causes behind long menstrual cycles.

1. Delayed Ovulation

If you want to find out if delayed ovulation is behind your longer menstrual cycle, the first thing to do is to find out when you ovulate. If you have a 39-day cycle, you most likely ovulate on day 25 of your cycle. Any ovulation that happens after day 21 of the menstrual cycle is considered delayed ovulation.

Start keeping track of your ovulation by tracking your cycles on a calendar or by using an app. Ovulation typically happens about two weeks before your period starts. If you don’t have periods that happen like clockwork, you can look for other signs of ovulation, such as:

  • A twinge or series of cramps on one side in your lower abdominal area.20% of women experience a slight pain, known as mittelschmerz, as the ovary releases an egg.
  • Charting your temperature. You’ll need a special thermometer called a basal body thermometer to take your temperature as soon as you wake up in the morning. Your body will reach its lowest temperature at ovulation and then rise immediately by about half a degree as soon as ovulation occurs.
  • Monitoring cervical fluid. During ovulation, the cervical fluid becomes clear and slippery with a consistency similar to raw egg whites. After ovulation, you’ll go back to a cloudy, non-slippery discharge.
  • Use an ovulation predictor kit.You can buy a kit that will predict when you’ll ovulate by monitoring the levels of luteinizing hormone in your body. It works similar to common pregnancy tests in that you just pee on a stick and wait for the result.

Delayed ovulation is often temporary and will correct itself over time. However, in some cases, medical attention may be required to address underlying problems.

2. Stress

It’s not all just in your head – stress can have a huge impact on your entire body, especially your menstrual cycle. Stress can be caused by everything from physical illness to a looming deadline at work. This heightened anxiety leads to an increase of cortisol, also known as “the stress hormone,” in your body.

Cortisol can short circuit your menstrual cycle, resulting in periods that are delayed or even missed entirely.

3. Weight

Losing or gaining weight can also have a huge impact on how regular your periods are. Changes of 20% or more in body weight can alter your hormone levels and your menstrual cycles as a result. Losing weight too fast or exercising too vigorously can also trigger biological stress responses. Eating disorders like bulimia or anorexia play a role in abnormal menstrual cycles as well.

4. Birth Control and Other Medications

Anytime you start hormonal birth control, you run the risk of experiencing irregular periods until your body adjusts to the new medication. Intrauterine devices (IUDs) are especially noted for causing long gaps between periods.

Some lesser known culprits behind irregular menstrual cycles include:

  • Anti-depressants and anti-psychotics
  • Chemotherapy
  • Steroids
  • Thyroid medications

5. Polycystic Ovary Syndrome (PCOS)

Up to 12% of – or 5 million – women in the US are diagnosed with polycystic ovary syndrome (PCOS) during their reproductive years. PCOS occurs when a woman has high levels of androgens, a hormone normally attributed to male characteristics.

High androgens can affect ovulation and, as a result, the length or frequency of menstrual cycles. They can also cause acne, thinning hair on the scalp, excess hair on the face, and insulin resistance – a condition that causes nearly half of women with PCOS to develop type 2 diabetes by the time they turn 40.

6. Hypothyroidism

Your thyroid is a small gland that produces important hormones that affect your entire body. Hypothyroidism is when your thyroid produces less hormones than your body needs. This can result in other imbalances, one of which includes an increase in prolactin.

Prolactin is tied to many biological functions, including ovulation and reproduction – which is why it is also known as the “milk hormone.” Too much prolactin can overpower other reproductive hormones like estrogen and progesterone, leading to prolonged menstrual cycles and missed periods.

Up to 12% of US citizens suffer from hypothyroidism, with women being ten times more likely to develop the condition. If you have hypothyroidism, chances are you’re also experiencing other symptoms besides delayed periods. Some of these include:

  • Dry skin
  • Brain fog and mental health issues
  • Muscle weakness
  • Slower metabolism and weight gain
  • Digestive issues like heartburn, constipation, and bloating
  • Thinning hair
  • Gallstones

Hypothyroidism can increase the risk for serious complications like heart attack and neurological issues, so if you’re experiencing the symptoms above, seek the advice of a medical professional.

7. Endometrial Cancer

No one wants to consider the “Big C” when trying to identify their abnormal menstrual cycles. But it’s important to recognize the symptoms of cervical and endometrial cancer when investigating irregular periods.

About 90% of women eventually diagnosed with endometrial cancer experience abnormal vaginal bleeding. This may present itself as long gaps between periods, but it also includes unusual spotting or discharge between menses or drastic changes to a woman’s menstrual cycle.

You should visit your OBGYN if you have already gone through menopause and begin to experience unusual vaginal discharge. Other worrying symptoms that might point to endometrial cancer are sudden weight loss, a mass or heavy feeling in the belly, and pelvic pain.

Cancer may be a scary diagnosis, but early detection is the key to successful treatment. Make an appointment with your doctor if there are any sudden or worrying changes in your menstrual cycle, and make sure you visit your OBGYN for your yearly checkup.

What’s Normal and What’s Not?

In most cases, what’s considered normal is what’s normal for you. Keeping track of the start date of your period for several months in a row will let you know what to expect from your menstrual cycle going forward. In addition to your period’s start date, consider tracking:

  1. Flow level – Is it light, heavy, or medium?
  2. Period length – How many days does your period last?
  3. Bleeding between periods – are you spotting or having unusual discharge between your periods?
  4. Pain level – Are you having worse cramps than usual?

 Consult a Doctor if:

  • You don’t have a period for more than 90 days, and you aren’t pregnant.
  • Your periods used to be regular, but now they’re not.
  • You experience menstrual bleeding for more than seven days.
  • You’re experiencing heavy bleeding, and you soak through more than one feminine hygiene product every hour or two.
  • Your periods occur more frequently than every 21 days.
  • Your periods occur less often than ever 38 days.
  • You are experiencing bleeding between periods.
  • You experience severe pain during menstruation.
  • Your irregular menstrual cycle is accompanied by other symptoms like extreme changes in weight, lower energy levels, digestive issues, or visible physical changes to your body.

Once you know what’s normal for you, you will be better equipped to recognize when there may be a problem that needs attention. Regular pelvic exams can ensure that any problems that are affecting your cycle are addressed as soon as possible.

Frequently Asked Questions

What does a long menstrual cycle mean?

Long menstrual cycles occur when a woman ovulates less often. This can be caused by many physical factors like age, illness, or stress. Abnormal cycles can affect fertility or be a sign of more serious underlying conditions, so it’s important to identify what is causing your delayed periods.

Is it normal to have a menstrual cycle over 40 days?

The average menstrual cycle in women is 28 days, but anything between 24 and 38 days is considered normal. If you consistently have menstrual cycles that last longer than 38 days, or you suddenly experience a drastic change in your cycle’s length, you should seek the advice of a medical professional.

At what age do periods become irregular?

Women naturally start to experience changes to their menstrual cycle when they go through perimenopause. Perimenopause is the transitional phase that occurs right before menopause. Some women enter perimenopause in their mid-30s, but it most commonly occurs to women in their 40s.

Why have my periods suddenly become irregular?

Having an irregular period from time to time is normal. But if you notice that your periods have become more irregular over time, there might be an underlying cause. Some common causes are delayed ovulation, stress, changes in weight, medication side effects, or a more serious underlying condition.

When should you see your doctor about missed periods?

You should see your doctor about abnormal periods when you have extreme or prolonged changes to your menstrual cycle. This might include missing three or more periods a year, experiencing increased flow or pain during your menses, or noting other physical changes not tied to your menstrual cycle. But it’s always a good idea to make an appointment with a trusted doctor when something feels “off” with your body or menstrual cycle.

4 Comments
  1. Hey, I’m 15 years old and I haven’t had my period in over 45 days. My cycle is usually long anyway, but should I be concerned? Thanks! P.S. I’m a virgin so there’s no way I’m pregnant.

    • Hello,

      First of all, none of us are doctors on this site, so if there is any doubt, please seek medical attention.
      Second, if you’re sure that you’re not pregnant, then the following may include what you’re experiencing.

      The amount of blood and how long our period lasts depends on hormones. Being that you’re a teen, your hormones are still fluctuating and balancing themselves out. It’s normal to experience irregular periods including skipping a month or two or even longer for the first few years. Some people have irregular periods all their lives.

      There are also other reasons that you may be missing periods. If you recently started or stopped medications, gained or lost a lot of weight, started or stop dieting or chanced your eating habits, started or stopped exercising or vigorous activities (sports), under a lot of stress…etc.

      I think you’re okay for now, but if you had a regular flow before this and you’ve suddenly missed three months of periods or more, I would advise going to a clinic or see a doctor.

      Good Luck <3

  2. you need to take a pregnancy test hun

  3. Hy every one I just missed Mi period two days back ,I just wnt 2 no whether I am pregnant or not? Thnx

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