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How Long Do Periods Last: What's Normal and When It Can Vary

How Long Do Periods Last: What's Normal and When It Can Vary

  • Rebekah Louise
    By: Rebekah Louise
    Reviewed By: Julie Lamonoff, CNM, OBGYN-NP, Shannon DeVita DNP, FNP-BC, CPNP-PC
    Updated:

We've all got that one friend who only bleeds lightly for 2 days and then she's done for the month. Frustrating isn't it?

But what about the rest of us? How long should our period last? What's a normal menstrual cycle and when should we be taking a trip to the doctor to talk about our periods?

How long do periods usually last?

Menstrual cycles happen once a month to prepare for a possible pregnancy. If a pregnancy doesn't occur then the lining of the uterus sheds and the period will start. A typical menstrual cycle is 28 days long and will occur around every 24-38 days. However, each woman is different, and cycles can vary each month [1]. Periods usually last somewhere between 4-8 days.

Key terms:

  • Menstruation - is also known as a period and is when blood and tissue leave the vagina. It usually happens once a month.

  • Menstrual cycle - is the hormonal process a woman's body goes through each month to prepare for a possible pregnancy.

  • Ovaries - are the reproductive gland in a female which sit in the pelvis on each side of the uterus. The ovaries produce eggs (ova) and female hormones.

  • Ovulation - is the release of an egg from one of a woman's ovaries. Ovulation typically lasts one day and occurs in the middle of a woman's menstrual cycle, about two weeks before she expects to get her period.

Signs your period is too heavy, long, or irregular

It's important to remember that what's 'normal' for your friend, will be different for you. However, there are some things that tell us whether our periods aren't quite right and we need to speak to our doctor.

Each period most women will lose 60 millilitres (around 2.02 ounces) of blood, which is around 4 tablespoons. On average that means it would take 4 hours for a pad or tampon to become full. If a woman is bleeding around 80 millilitres each period (around 2.70 ounces) she is considered to have heavy bleeding [6].

Physical signs of heavy periods include:

  • Regularly needing to change pads, tampons, or reusable menstrual products after only one or two hours.

  • Using two or more menstrual products at the same time to prevent leaking.

  • Large clumps of blood in your pad or when you remove your tampon.

  • Feeling tired and sluggish.

Heavy periods can have a huge impact on our emotional state too such as,[10]:

  • A negative impact upon work productivity.

  • Our family life and social relationships and events.

  • Our sexual relationships.

It's important to recognize that heavy menstrual bleeding has a major impact on a woman's quality of life, and any interventions should aim to improve this rather than just focusing on blood loss.

If your periods are longer than 7 days on a regular basis then it's considered a long period and you should speak to a doctor [3], [11]. Longer lasting periods are often referred to as menorrhagia, meaning someone is experiencing heavy periods. Around 1 in every 20 women has menorrhagia [4].

If you experience different amounts of time in between your periods then they are irregular. Again, this may be normal for you, especially if you don't have any other period-related symptoms such as painful cramps, blood clots, or heavy bleeding, and doesn't necessarily mean there is a problem. It's especially common for younger girls to have irregular periods during the first 2-3 years after starting their period. It's also common for women entering perimenopause to experience irregular periods. Note that you can still get pregnant despite having irregular periods.

Practice guidelines published in Best Practice & Research Clinical Obstetrics & Gynecology found that between 14% and 25% of women have abnormal uterine bleeding, including heavy menstrual bleeding [2].

Is it normal for periods to be short?

Women's cycles can vary in length. For some, this is normal, for others, a trip to the doctor might be needed.

Birth control pills may cause bleeding in the first few weeks and it may take around 3 months for your periods to settle down. You may notice your periods are lighter when taking contraceptive pills as the lining of your uterus isn't as thick.[8], [12].

There are a range of reasons why girls and women experience lighter and shorter periods, these include [13]:

  • Puberty

  • Stress

  • Over-exercising and under-eating and losing too much body fat

  • Taking birth control pills and other forms of contraception

  • Certain medications

  • Perimenopause

4 factors that affect how long your period lasts

There are a number of factors that can affect how long your period may last for. These include:

1. Menstruation can change with age

Girls begin their period around the age of 8-12 years. When their periods first start they are likely to last around 5 days. During the first 2-3 years, it's common for the period to be irregular. After this, they will begin to arrive every 4-5 weeks and still only last for around 5 days [5]. During the teenage years, it's common for periods to be heavier and can become lighter in your 20's and 30's, and the menstrual cycle will typically last between 24-38 days.

Entering perimenopause also has an effect on how regular the menstrual cycle is. Women usually enter this stage in their lives around the age of 40.

2. Birth control's influence on the length of periods

All types of hormonal birth control can have an effect on the menstrual cycle, especially in the first 3-6 months of using it.

When using the combined pill, the contraceptive patch, the contraceptive injection, and the vaginal ring, it stops an egg being released from the ovary. If you still have a monthly bleed, this may be lighter and is called a withdrawal bleed.

The birth control pill and period length

Whether taking a combined pill which contains estrogen and progestin, or a progestin-only pill, it's likely that you will experience breakthrough bleeding or spotting in the first few months.

If you're taking the progestin-only pill you may also spot if you forget to take the pill, even if it's a couple of hours difference. The pill works by stopping ovulation and preventing the male's sperm from reaching the egg [8].

It can take around three months for your periods to return to a regular pattern once you stop using the pill.

The birth control injection or implant and period length

The hormonal implant is a tiny tube that is placed underneath the skin in the arm. The tube releases progesterone which inhibits the pituitary gland, to stop the ovaries from releasing an egg. The most common side effect of the implant is light and irregular bleeding [16].

The injection contains progesterone and is given every 3 months. The injection stops the ovaries from releasing an egg and thickens the fluid at the top of the womb. The injection can cause irregular bleeding and may happen during the first few months of having the injection, but this may settle down as you have more injections [17].

The IUD and period length

The copper IUD may cause you to have irregular bleeding for 3-6 months and may cause heavier or longer periods [15].

The progestin IUD can also cause irregular bleeding for 3-6 months. This should improve over time, become lighter and may disappear [15]. In fact, a significant number of women no longer get their period while using an IUD.

The vaginal ring and period length

The vaginal ring is a flexible ring that is placed inside the vagina, it contains both estrogen and progesterone. You wear the ring for 3 weeks and then remove it to have a period during the 4th week. However, using the ring may cause irregular bleeding or spotting [18] within the first few months.

The emergency contraceptive pill and period length

Emergency contraception can change the timing of your next period. It may also cause spotting or irregular bleeding during the week or month after you've taken the pill [19].

3. Underlying health conditions and irregular periods

There are different health conditions that can cause irregular, heavy, or prolonged bleeding such as [20],

  • Ectopic pregnancy

  • Endometriosis

  • Polycystic ovary syndrome

  • Adenomyosis

  • Polyps

  • Fibroids

  • Ovulatory Dysfunction

If you think you may be experiencing any of the above, it's important to go and see your doctor.

4. Sexually transmitted infections (STI's) and irregular periods

Sexually transmitted infections such as chlamydia and gonorrhea can cause irregular bleeding and spotting between periods [9]. Pelvic inflammatory disease is caused when a bacterial infection spreads from the vagina or the cervix to the reproductive organs. This infection can cause bleeding between periods, during and after sex, and heavy periods [21].

When to see a doctor about abnormal periods

Abnormal periods vary person to person. Below are some signs that your period is abnormal [22].

  • Your periods last longer than 7 days.

  • You experience a cycle less than 24 days or more than 35 days.

  • You have irregular periods.

  • You are experiencing heavy bleeding and you're having to change your pad or tampon every 1-2 hours.

  • You are seeing blood clots of around 1 inch in size

  • You've started bleeding after you've gone through menopause.

Solutions for long and heavy periods

Before trying to treat long or heavy periods, it's vital that you speak with your doctor or nurse first to rule out any health conditions and receive any necessary treatment.

If there are no obvious reasons for your long or heavy periods then the doctor may suggest you begin a form of contraception. At first, this may cause irregular bleeding or spotting. However, over time, this should settle and help your periods to fall into a regular pattern.

Not all women wish to use contraception and may choose to look at other ways to manage their long or heavy periods such as,

Maintaining a healthy weight

Weight can influence menstrual cycles. Losing too much weight or losing weight quickly can cause irregular cycles or your period may stop. Also, women who are obese may have irregular periods [23].

Delaying or skipping periods

Heavy or prolonged bleeding can be emotionally and physically draining. With the advice and support of your doctor, it is possible to delay or sometimes stop your periods for a longer amount of time.

If your doctor is in agreement, they may prescribe you the combined contraceptive pill. If you take your packets back-to-back, you will probably skip a period. However, one side effect of taking pill packets together can be unexpected bleeding.

The IUD and vaginal ring can also be used to delay or prevent a period.

In summary

The length of a woman's period is unique to her, however, there are factors that can influence menstruation, including health issues and birth control. If you notice any changes to your menstrual cycle or period then it's important to speak to your doctor.

Sources

  1. Womenshealth.gov.Menstrual Cycle. Updated March 16, 2018.

  2. Whitaker L. Critchley H. Abnormal uterine bleeding. Published November 25, 2015

  3. National Health Service UK. Irregular Periods. Reviewed April 9, 2018

  4. Cleveland Clinic. Menorrhagia (Heavy Menstrual Bleeding). Reviewed August 3, 2018

  5. Kids Health. All About Periods. Reviewed October 2018

  6. NCBI. Heavy Periods. Reviewed May 4, 2017

  7. Abraham G. Nutritional factors in etiology of the premenstrual tension syndromes. July 1983

  8. Young Women's Health. Birth Control Pills. Updated June 8, 2020

  9. National Health Service . Sexually transmitted infections. April 9, 2018

  10. NCBI. The prevalence and impacts heavy menstrual bleeding on anemia, fatigue and quality of life in women of reproductive age. Mar- Apr 2019

  11. Centres for Disease, Control, and Prevention. Heavy Menstrual Bleeding. December 2017

  12. Young Women's Health. Medical Uses of the Birth Control Pill. June 2020

  13. Healthline. What Causes Your Period To Be Shorter or Lighter Than Normal. December 2018

  14. Mayo Clinic. Perimenopause. May 2019

  15. Medical News Today. What are the side effects of an IUD?. August 2018

  16. Centre for Women's Health. Hormonal Implants. April 2019

  17. Contraception Choices. Injection.

  18. Mayo Clinic. Vaginal Ring. February 2020

  19. ACOG. Emergency Contraception. June 2020

  20. Wouk, N. & Helton, M. American Family Physician. Abnormal Uterine Bleeding in Premenopausal Women. April 2019

  21. Mayo Clinic. Pelvic Inflammatory Disease. April 2020

  22. American Family Physician. Abnormal Bleeding During Your Period. January 2012

  23. The Office on Women's Health. Weight Loss and Women. March 2019

  24. PubMed. Herbal Medicines in Idiopathic Heavy Menstrual Bleeding: A Systematic Review. October 2016

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