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    22 Top Questions About Your Menstrual Cycle Answered

    Updated 24 January 2022 |
    Published 04 April 2019
    Fact Checked
    Reviewed by Kate Shkodzik, MD, Obstetrician and gynecologist
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    Periods are characterized by bleeding from the uterus through the vagina and indicate the beginning of a new reproductive cycle. While periods are a normal biological occurrence, there are still some questions surrounding this phenomenon.

    Kate Shkodzik, a medical specialist at Flo, answers the most commonly asked questions about periods.

    Why do we get periods every month?

    Periods, or menstruation, are the cyclical bleeding from the uterus that occurs about every month or so, and are a part of the normal menstrual cycle. The changes in hormone levels, as well as in the ovaries and uterus, that happen during a menstrual cycle are all aimed at achieving pregnancy. When pregnancy doesn’t occur, the uterus sheds its inner lining along with blood and mucus through the cervix and vagina due to a sharp decrease in estrogen and progesterone.

    How long without a period is normal?

    Menstrual cycles that are 21–35 days long are considered normal. A period is considered late if it’s more than five days past its expected start date. You might also be wondering how late it can be without being pregnant.

    Sometimes a period delay can be due to stress or rapid weight loss. 

    More rarely, it may be a sign of an endocrine condition like polycystic ovary syndrome (PCOS), thyroid dysfunction, hyperprolactinemia, or another health issue. If your period is late, take a pregnancy test and don’t hesitate to visit a health care provider.

    If your periods are late for several months, make sure to consult a health care provider to figure out possible underlying reasons.

    Is it normal to have periods twice a month?

    For menstrual cycles that are 21 days long, it’s possible to have a period twice during one calendar month. However, bleeding twice or more during one menstrual cycle, blood after sex, or bleeding that stops and then starts again after several days could indicate a health issue. 

    Hormonal imbalance, ovarian cysts, endometriosis, uterine fibroids, pelvic inflammatory disease, and cervical neoplasia can cause irregular bleeding. If there is any bloody vaginal discharge outside of a normal period, visit a health care provider to find out what’s causing it.

    Does a “normal” cycle really exist?

    Read medically reviewed articles on topics like this

    When is a menstrual cycle too short?

    The length of the menstrual cycle is the number of days between the first day of one period and the first day of the next period. Cycles between 21 and 35 days are considered normal.

    If menstruation starts more frequently than every 21 days, it may be considered too short. 

    What are some reasons for a period delay?

    There are many possible reasons for a late period. For people who are trying to conceive or had unprotected sex, pregnancy is the most likely reason. Late periods can also be caused by medical conditions such as PCOS, high levels of prolactin, or thyroid issues. 

    Sometimes using hormonal birth control methods can also cause late periods.

    What causes irregular periods?

    There are also many possible reasons for irregular periods. The most likely are excessive stress, extreme exercising, or extreme weight fluctuations. Just like with late periods, irregular periods can also be caused by PCOS, high levels of prolactin, or thyroid issues.

    Do irregular periods influence the ability to get pregnant?

    Irregular periods can influence the ability to get pregnant. Stress, bodyweight fluctuations, PCOS, hyperprolactinemia, and hyper- or hypofunction of the thyroid gland can all cause irregular periods. Irregular periods are usually associated with problems with ovulation, which may influence the ability to get pregnant. 

    How long will I have irregular periods after a miscarriage?

    It usually takes four to six weeks for periods to start again after a miscarriage. Sometimes it can take up to three months for periods to become regular. 

    Try to relax, rest, maintain a healthy diet, and exercise regularly. If the menstrual cycle doesn’t become regular by three months after the miscarriage, contact a health care provider to find out the cause.

    Should I worry if my period is late by one day?

    There is usually nothing to worry about if a period is a day late. Taking a pregnancy test can help confirm if pregnancy may be the cause.

    My period is 10 days late. Am I pregnant?

    Periods that are more than five days past due are considered late. There are a variety of reasons for late periods, including pregnancy. A home pregnancy test detects the presence of human chorionic growth hormone, or “pregnancy hormone,” in urine. Blood tests will also show this hormone and its quantity.

    I haven’t had sex. Why is my period late?

    There are many possible reasons for a late period. The most likely are excessive stress, extreme exercising, and fluctuations in body weight. Reproductive issues like PCOS and pelvic inflammatory disease can also cause late periods.

    High levels of prolactin or thyroid issues (hyper- or hypofunction) can as well. Sometimes using hormonal birth control methods can also cause late periods.

    Can adapting to new birth control pills cause a period delay?

    Adapting to new birth control pills can cause a period delay. A pregnancy test can confirm if a period is late due to pregnancy. It may take around three months for the body to adapt to new birth control.

    Can I get pregnant from sex two days before my period starts?

    Pregnancy is possible on any day of the cycle, but the chances are higher during the fertile window. Ovulation is when the egg is released from the ovary, and it normally happens 10 to 16 days before the next period starts. 

    Taking into account that an egg cannot live for more than 24 hours, and sperm can survive for up to five days, the days with the highest chances of conception are five days before ovulation and 24 hours after it.

    Is it normal to get emotional before a period?

    The period after ovulation and before menstruation is called the luteal phase. During this phase, the body is getting ready for pregnancy in case fertilization takes place. The main hormone during the luteal phase is progesterone.  

    Anxiety, mood fluctuations, headache, weight gain, and increased hunger are common premenstrual symptoms. Cyclic changes in progesterone and estrogen, excess prostaglandins, and fluctuations in serotonin levels are all responsible for premenstrual symptoms. 

    About 80 percent of women experience premenstrual symptoms. As long as these symptoms do not disrupt everyday life, there is nothing to be concerned about. 

    I have a big increase in hunger before my period. Is that normal?

    Increased hunger, anxiety, mood fluctuations, headache, and weight gain are all common premenstrual symptoms. Premenstrual symptoms are the result of cyclic changes in progesterone and estrogen, and fluctuations in serotonin. 

    Most people experience premenstrual symptoms before their period. As long as these symptoms do not disrupt everyday life, there is nothing to be concerned about.

    Why is my period blood black?

    It is absolutely normal for period blood to be black or dark brown at the very beginning or at the end of a period. At the beginning and end of menstruation, the flow is usually slow, and blood on the pad or tampon is old blood that has been exposed to oxygen.

    Menstrual discharge consists mostly of parts of the inner lining of the uterus — the inner lining of the uterine wall — and blood. It moves from the uterus to the vagina, where it is oxidized. Blood contains iron, which becomes black after oxidation. However, if menstrual blood is black throughout the whole period, it could indicate a problem. Be sure to contact a health care provider in this case.

    Can antibiotics affect your period?

    Antibiotics do not cause late, early, or absent periods or heavy and prolonged menstruation. The most likely cause for an irregular period on antibiotics is usually the infection for which an antibiotic was prescribed. 

    There is a long list of side effects for various antibiotics, but irregular or painful periods are not typically included. Rifampin is an exception. It is an antibiotic that is used to treat tuberculosis and has been proven to cause irregular or painful menstruation.

    How can I make my period come earlier?

    People who are taking birth control pills can switch to placebo pills to schedule their period. However, taking placebo pills during the first 10 days of the pack can lead to heavy and prolonged periods. It’s better to consult a health care provider before making a switch.   

    Some people claim that vitamin C, ginger, parsley, turmeric, or other herbs can induce periods. However, there is no reliable scientific evidence that they work. 

    I’m bleeding after taking the morning-after pill. Is it my period?

    The morning-after pill is a form of emergency contraception. It contains levonorgestrel, which is a synthetic form of the hormone progesterone. There is another type of emergency contraception that contains ulipristal acetate. 

    The morning-after pill may cause unexpected uterine bleeding that should end before the next normal period starts. 

    Emergency contraception pills can also cause the next period to come late or early or be heavier and more painful. The morning-after pill should not be used as a routine method of birth control.

    Is it ok to feel different depending on the day of the cycle?

    The menstrual cycle can affect people’s emotional and physical condition. This happens because of hormonal changes during the cycle. As long as these changes don’t disrupt everyday life or bring any discomfort, there is no reason for concern.