What’s the First Day of Your Period?

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Learning about your menstrual cycle and when it officially starts
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Experts say that while the length of your menstrual cycle varies, the typical timeline is every 28 to 31 days. [1] Knowing when the first day of your menstrual cycle is a question often asked by your healthcare provider, and it can help you to make informed decisions about your health and family planning. Studies show that by tracking your period, you can calculate the first day of your menstrual cycle to stay on top of your reproductive health. [2]

Things You Should Know

  • The first day of your menstrual cycle starts on the first day of your period.
  • On average, you’ll usually bleed for 3 to 5 days, but the length of your cycle could fluctuate.
  • The first day of your next period typically starts within 21 to 35 days of your last cycle.
Method 1
Method 1 of 3:

Determining the First Day of a Period

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  1. Menstruation begins after puberty in people with the required, functioning organs; womb, ovaries, etc. The menstrual cycle is divided into separate phases (follicular, ovulation and luteal) and the first day of your cycle describes the luteal phase that involves your uterus shedding its blood-rich lining through the vagina, known as menstruation or a period. [3]
    • Menstrual cycles tend to occur every 21 – 35 days in adults and 21 – 45 days in younger teenagers. The cycle is counted from the first day of your period to the first day of your next period.
    • Menstrual cycle is linked to fluctuations in estrogen levels, luteinizing hormone and follicular stimulating hormone. During the first half your cycle (follicular phase), your body is estrogen-rich and the uterine lining becomes thickened in preparation for implantation of a fertilized egg.
    • Halfway through your cycle, your ovary releases an egg into your fallopian tube. This phase is known as ovulation. Conception can occur if intercourse happens in the couple days preceding ovulation. If it occurs at the time of ovulation, the chance of pregnancy is small, because there is not enough time for the sperm to travel to the egg.
    • If an egg released during the ovulation phase does not get fertilized and implant within the lining of the uterus, your progesterone and estrogen levels will drop, causing the uterus to shed its thickened lining during the luteal phase.
  2. Understanding the days of your cycle empowers you to make decisions about your health and family planning. To begin determining the first day of your period and the length of your cycle, start by numbering the days of your cycle from the first day of your next period. [4]
    • Day one of your cycle occurs with the start of your period. Mark your calendar with "X" on the day your period starts.
    • Bleeding tends to last three to five days on average, but this may fluctuate on individual basis. [5]
    • On the seventh day of your menstrual cycle, bleeding has usually ceased and your ovaries begin to form follicles in preparation for ovulation. This is the result of an increase in estrogen between days four to seven. [6]
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  3. Tracking your period beginning with day 1 of your cycle helps you to learn general trends in your menstrual cycle and determine the first day of your next period. [7]
    • On average, most menstruating adults have a 28 day menstrual cycle. This means there are 28 days between the first days of each period.
    • However, your menstrual cycle may be slightly shorter or longer (adults tend to have cycles that run 21 – 35 days. It is important you track your periods for a few months to determine the length of your cycle.
    • As long as you get regular periods at more or less the same cycle interval, then your menstrual cycle is healthy.
    • You can track your menstrual cycle by making a note on a calendar or, if you prefer, you can also use a smartphone app like Fertility Friend.
  4. Establishing your cycle length helps you anticipate when you period will start. [8]
    • Once you have tracked your periods and established your cycle length, you can start marking your calendar to determine the first day of your subsequent periods.
    • For example, if your cycle length is 28 days, mark your calendar (starting from the first day of your next period) with an “X” for every 28 days — this will represent the first day of your subsequent periods.
    • If you are taking hormonal birth control pills, you will typically have the 28-day cycle due to the scheduling of the pills. Many packs of pills contains 21 hormonally active pills and seven sugar pills. On the day you run out of hormonally active pills, you typically begin your period. The period lasts the seven days (or less) during which you are eating the sugar pills. You may have no pills to take for seven days, it depends on the type of contraception pill you use.
    • If you are taking extended or continuous use hormonal birth control pills, your periods will happen less frequently. Seasonale contains 84 active pills and seven days of inactive pills. In this case you would have a 91 day cycle.
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Method 2
Method 2 of 3:

Signs Your Period is Coming

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  1. You may experience symptoms one to two weeks before the first day of your period. The symptoms usually go away after you start bleeding. PMS is different for everyone, and it is helpful if you document your symptoms as you track your period. [9]
    • Expect at least one PMS symptom as part of your menstrual cycle.
    • Your symptoms can be both physical and emotional.
  2. Many people experience crying spells, anxiety, mood swings, or depression before their period starts. You also may experience fatigue and irritability. If changes in your mood do not end after your period starts, or you feel like your daily life is being impacted, you need to see your doctor. [10]
    • 30 minutes of moderate-intensity exercise and strength training two or more days a week can help with depression and fatigue that you may experience.
  3. You may experience abdominal bloating, constipation, fluid retention, or diarrhea prior to your period. This can result in weight gain before your period starts. [11] Again, these symptoms should end within four days of your period starting. See a doctor if they continue.
    • You can limit your salt intake and eat smaller, more frequent meals to alleviate some of the bloating and fluid retention. [12]
    • Taking a diuretic can help your body get rid of excess fluid and reduce bloating and weight gain as well. Medications like Pamprin and Midol contain diuretics.
  4. Breast tenderness, joint or muscle pain, and headaches are common symptoms. You can take over-the-counter pain medication such as ibuprofen, aspirin, or naproxen to relieve these symptoms. [13]
    • Acne is also a common physical symptom that your period is on the way. [14]
  5. If you experience five or more of these symptoms and find that your PMS is keeping you from doing your usual activities, you may have premenstrual dysphoric disorder (PMDD). Your doctor may prescribe you antidepressants, prescription pain medication, or the Yaz birth control pill to manage your symptoms. [15]
    • Counseling and therapy may also be helpful for dealing with the emotional aspect of PMDD.
    • You should also see your doctor if your symptoms do not go away after your period starts, or you begin to see a change in the frequency or volume of your symptoms.
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Method 3
Method 3 of 3:

Menstrual Problems

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  1. If you ever have any health concerns regarding your period, make sure you talk to your doctor. You should also consult your doctor if your menstrual cycle is abnormal or becomes abnormal suddenly. Some factors that should warrant a discussion with your doctor include: [16]
    • If you do not start your period by age 15, you should contact your doctor, as you may have a hormonal imbalance that is affecting the rest of your body as well. [17]
    • If your period is extra painful and you experience very heavy bleeding or bleeding that lasts longer than a week.
    • If your period becomes irregular, delayed, or you have bleeding between established cycles.
  2. Amenorrhea is the lack of a menstrual period. People with the functional, required organs should start having periods by the age of 15 and if you or your child has not received their first period by the age of 15, consult your doctor. [18]
    • If you have missed your period for more than three cycles after having regular periods, you may be experiencing secondary amenorrhea. Secondary amenorrhea may be a symptom of polycystic ovary syndrome. [19] The most common cause of secondary amenorrhea is pregnancy.
    • Amenorrhea may result if you are unhealthy and your body is not able to support a regular period. This may be because of excessive stress, a hormonal disorder, or an eating disorder.
    • If your amenorrhea is hormonally linked, then your fertility may be at risk. Talk to your doctor right away, especially if you are concerned that you suffer from polycystic ovaries.
  3. Dysmenorrhea is a condition in which periods are unbearably painful. You may be able to take over-the-counter medication, such as ibuprofen, to ease very painful cramping but if this condition continues, consult your doctor. [20]
    • In teens and younger adults, dysmenorrhea is often caused by an excessive amount of prostaglandin. You may be able to regulate the amount of this hormone in your body by eating a healthy diet and maintaining a healthy weight most of the time.
    • In more mature people, dysmenorrhea may manifest due to a serious medical condition such as endometriosis, fibroids, or adenomyosis. [21]
  4. You should know what a normal period feels like if you have had regular periods in the past. Keep an eye out for abnormal bleeding. Talk to a doctor immediately if you have irregular bleeding. [22]
    • Discomfort and bleeding after sex are serious signs of possible medical conditions. Make sure you talk to your doctor if any sexual activity or intercourse results in bleeding.
    • Spotting between periods and heavy bleeding during your period can result in discomfort and are also warning signs that you need to heed.
  5. Different factors can lead to abnormal periods. Maintaining a healthy weight and seeing your doctor about possible illnesses help you to have normal periods.
    • Dysfunctional ovaries can lead to hormonal dysfunction and cause you to have abnormal periods. Polycystic ovary syndrome and premature ovarian insufficiency are two examples. [23]
    • Abnormalities in your reproductive structures caused by disease or infection can also cause you to have abnormal periods. Have your doctor check you out for endometriosis, pelvic inflammatory disease, or uterine fibroids. [24]
    • High stress, low body weight, and eating disorders take a large toll on your body and can disturb normal menstrual cycle. [25]
  6. You should have annual pelvic exams to ensure that any menstrual irregularities are diagnosed as soon as possible. [26] Tracking your period and monitoring your symptoms can help your doctor diagnose you properly and create a treatment plan. Your doctor may prescribe you oral contraceptives or progesterone to treat your menstrual irregularities. [27]
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Expert Q&A

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  • Question
    My period lasts for a day. What's wrong?!
    Lacy Windham, MD
    Board Certified Obstetrician & Gynecologist
    Lacy Windham, MD, is a Board-Certified Obstetrician & Gynecologist in Cleveland, Tennessee. Dr. Windham attended medical school at the University of Tennessee Health Science Center in Memphis. Her residency was completed at Eastern Virginia Medical School in Norfolk, Virginia. She was the recipient of multiple awards during her residency training, including Most Outstanding Resident in Maternal Fetal Medicine, Most Outstanding Resident in Oncology, Most Outstanding Resident Overall, and Special Award in Minimally Invasive Surgery.
    Lacy Windham, MD
    Board Certified Obstetrician & Gynecologist
    Expert Answer
    If you period is coming regularly, but only lasts one day, this is likely normal. There is a wide range of variation in how much bleeding occurs during menses. It is still worth consulting with your gynecologist.
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      Tips

      • When getting closer to the first day, you may also start to have mood swings and other PMS signs.
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      • Just counting the days from the start of one period to the start of the next is not enough to determine the length of your menstrual cycle. Chart this information for several months to see what the average length is, then you can use that data for planning purposes.
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      Warnings

      • Consult a doctor if there is a sudden change in your menstrual cycle, or if you begin to feel sharp abdominal pain while menstruating.
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      References

      1. ↑ https://www.nhs.uk/conditions/periods/fertility-in-the-menstrual-cycle/
      2. ↑ https://www.womenshealth.gov/menstrual-cycle/your-menstrual-cycle
      3. ↑ http://www.womenshealth.gov/publications/our-publications/fact-sheet/menstruation.html
      4. ↑ https://www.plannedparenthood.org/learn/birth-control/fertility-awareness/whats-calendar-method-fams
      5. ↑ http://www.womenshealth.gov/publications/our-publications/fact-sheet/menstruation.html
      6. ↑ https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/menstrual-cycle
      7. ↑ https://www.plannedparenthood.org/learn/birth-control/fertility-awareness/whats-calendar-method-fams
      8. ↑ http://www.womenshealth.gov/publications/our-publications/fact-sheet/menstruation.html
      9. ↑ https://www.womenshealth.gov/menstrual-cycle/premenstrual-syndrome
      1. ↑ https://familydoctor.org/condition/premenstrual-syndrome-pms/
      2. ↑ https://familydoctor.org/condition/premenstrual-syndrome-pms/
      3. ↑ https://health.clevelandclinic.org/11-diet-changes-that-help-you-fight-pms/
      4. ↑ https://www.plannedparenthood.org/learn/health-and-wellness/menstruation/what-can-i-do-about-cramps-and-pms
      5. ↑ https://familydoctor.org/condition/premenstrual-syndrome-pms/
      6. ↑ http://www.womenshealth.gov/publications/our-publications/fact-sheet/premenstrual-syndrome.html
      7. ↑ https://www.womenshealth.gov/menstrual-cycle/your-menstrual-cycle#h
      8. ↑ http://www.womenshealth.gov/publications/our-publications/fact-sheet/menstruation.html
      9. ↑ https://my.clevelandclinic.org/health/diseases/3924-amenorrhea
      10. ↑ https://www.nichd.nih.gov/health/topics/amenorrhea/Pages/default.aspx
      11. ↑ https://my.clevelandclinic.org/health/diseases/4148-dysmenorrhea
      12. ↑ https://www.acog.org/womens-health/faqs/dysmenorrhea-painful-periods
      13. ↑ https://my.clevelandclinic.org/health/diseases/15428-uterine-bleeding-abnormal-uterine-bleeding
      14. ↑ https://my.clevelandclinic.org/health/healthy_living/hic_Coping_with_Families_and_Careers/hic_Normal_Menstruation/hic-abnormal-menstruation
      15. ↑ https://my.clevelandclinic.org/health/healthy_living/hic_Coping_with_Families_and_Careers/hic_Normal_Menstruation/hic-abnormal-menstruation
      16. ↑ https://my.clevelandclinic.org/health/healthy_living/hic_Coping_with_Families_and_Careers/hic_Normal_Menstruation/hic-abnormal-menstruation
      17. ↑ https://www.plannedparenthood.org/learn/health-and-wellness/wellness-visit/what-pelvic-exam
      18. ↑ https://www.aafp.org/afp/2012/0101/p35.html

      About This Article

      Article Summary X

      To determine the first day of your menstrual cycle, watch for signs that your period is coming and monitor the length of your cycle. You’ll probably notice emotional or physical symptoms around 2 weeks before your period starts. These can include changes in your mood, tenderness in your breasts, and constipation. Then, mark your calendar on the first day of your period so you can remember it in the future. Mark your calendar again on the first day of your next period, which will give you the length of your menstrual cycle. Once you have this information, you’ll be able to roughly predict when the first day of your cycle will be. Typically, a menstrual cycle lasts 28 days, but it's normal for it to vary by a day or two depending on the person. Remember to see your doctor if you have any health concerns about your period, or if your menstrual cycle is abnormal. To learn more from our Medical co-author, including what can cause abnormal periods, keep reading!

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