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Main causes of dark period blood

Generally, dark and a low-volume period is normal and does not indicate any health problems, especially if it occurs at the beginning or end of menstruation. However, when this type of menstruation is recurring, it can be a sign of hormonal changes, uterine problems, stress or sexually transmitted diseases, for example.

This can also happen, when women start taking the contraceptive pill for the first time, changes the pill or uses the morning-after pill. In these cases, menstruation can also become darker or have the color of coffee grounds, returning to normal in the next cycle.

Main causes of dark period blood

Main causes of dark period blood

Black, brown, or coffee-type menstruation may be caused by:

1. Pregnancy

The onset of a small pinkish, brownish or dark reddish bleeding in color is common in the first weeks of pregnancy because the embryo is attaching itself to the walls of the uterus.

However, when this bleeding occurs at a later stage of pregnancy or is accompanied by other symptoms such as abdominal pain, shoulder pain, dizziness or excessive fatigue it may indicate the development of ectopic pregnancy or abortion, so it is recommended you go to the obstetrician to verify if there is any problem.

2. Emotional changes

Some changes in a woman's emotional state, such as excessive stress or depression, can affect the structure of the uterus by reducing the thickness of its walls. This change delays the flaking of the uterus wall cells and, therefore, facilitates blood oxidation, making the period darker.

3. Hormonal changes and menopause

When hormonal changes arise due to thyroid problems, or even, by menopause, it is very common that the period becomes dark and comes in small quantities. This change is also very common when switching the contraceptive pill or when the woman is not breastfeeding very often and the breastfeeding pill is not enough to avoid bleeding.

4. Sexually transmitted diseases

Sexually transmitted diseases caused by bacteria, such as gonorrhea or chlamydia, for example, cause a more rapid degradation of menstrual blood, making menstrual blood darker. In addition, this type of period is usually accompanied by a foul smell, brown discharge before or after menstruation, pelvic pain and a fever above 38º C. 

5. Endometriosis and other conditions

Endometriosis consists in the growth of endometrial tissue outside the uterus. This type of problem and other conditions such as adenomyosis can cause severe pain in the pelvic region and dark blemishes, such as the color of coffee grounds, that can occur both inside and outside of menstruation.

In these cases, the period, besides being dark, is also more prolonged, and may take more than 7 days to end. In case of suspicion you should go to the gynecologist so he can exam you, ask for tests and indicate the antibiotics you can take, or another form of treatment, such as surgery, for example.

6. Post-partum

Another situation in which dark period blood is normal is in the postpartum stage because the uterus takes about 45 days to return to its normal size and there is bleeding during this period. At this stage this bleeding is not exactly menstruation, but the coloration is dark and may confuse many women, but this is a normal and is expected.

If your period comes with clots, read why your period can come with clots and skin?

When should you go to the doctor

Usually changes in menstrual bleeding are normal and do not indicate problems, but the gynecologist should be consulted if other symptoms or signs also appear, such as:

Period lasting more than 7 days;

  • Stay without menstruation for more than 3 months;
  • Have bleed-offs;
  • Pain in the intimate region;
  • Fever above 38º C;
  • Dizziness;
  • Pale skin overall or below the nails.

It is also important to remember that in cases of suspected pregnancy, the appearance of dark bleeding, with pieces or in large quantities is also a reason to seek the doctor because it may be a miscarriage, and a curettage may be necessary to clean the uterus. 

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