Red and Black

This question is from a reader. Feel free to contact me with questions!


Question:
My menstrual blood is sometimes brown instead of red. Is there something wrong with me?

Answer:
No, you're fine.

Blood is bright red when it is oxygenated. Blood has hemoglobin, which can bind oxygen molecules. In the lungs, oxygen is passed from the lungs into the blood, turning it bright red. As the blood is transported through the body, its oxygen is transferred to the organs it passes through, and the blood becomes darker (dark red, bluish). By the time it reaches the veins (which bring blood back to the heart), much of the oxygen content has reduced.

During menstruation, blood is shed by the lining of the uterus, and that is usually bright red blood. The blood does not always come out immediately. It can sit in the uterus, cervix or vagina for some time before the woman sees the blood. In that time, the blood can be oxidized (which is different from oxygenated) - it involves a transfer of electrons, rather than just binding of oxygen to hemoglobin. When blood is oxidized, it turns brownish or black.

Therefore, brownish period blood is merely blood that has been sitting around for a while. All blood, after being exposed to air, will eventually turn brown or black.

(Incidentally, this is why stool can sometimes be black - because there is gastrointestinal bleeding. If you have black stools, see your doctor)

Irregular Periods

Question: 
My periods are irregular and infrequent. Is that OK?

No, there may be a problem.

Regular menstruation usually occurs monthly. For most women, this is highly predictable, and comes every 28-30 days. Other women might have shorter or longer cycles (26 or 32 days apart, for example), or variable cycles, but they will still have a monthly period. These women all have regular menstruation.

When the period is irregular, meaning it does not come reliably every month, there is a problem. Most of the time, the problem is that the body is not ovulating, also known as anovulation.
Here is a nice video from womenshealth.gov showing the process of menstruation.

To understand why anovulation happens, it is important to understand how the female hormones work.
Estrogen and progesterone are the most commonly known female hormones. They are very important in controlling the normal function of a woman's reproductive system.

This graph shows the hormonal fluctuations that are needed to have a normal menstrual cycle:

Source: DevBio

Estrogen (blue) causes the uterine lining (the endometrium) to thicken in preparation for ovulation. Progesterone (purple) stabilizes the endometrium, preventing the blood from spilling out. Just before menstruation, both estrogen and progesterone drop quickly (see day 28), and the loss of progesterone allows the thickened uterine lining to bleed out.

Two other hormones that are less well-known also play a role. Follicle-stimulating hormone (FSH, orange) causes the ovaries to develop an egg, and lutenizing hormone (LH, red) peaks and causes the ovary to release that egg (ovulation).

When these four hormones do not fluctuate they way they're supposed to, normal ovulation and menstruation don't happen. Without the increase in LH, the body doesn't know to release the egg. And without the decrease in progesterone, the uterus doesn't shed its lining.

In many women with irregular menstruation, the periods come infrequently, and they can go several months without bleeding. When the period does come, it can be heavy because of the heavy buildup of the uterine lining, and it often lasts longer because there is no hormonal input telling the uterus to stop bleeding.

Why are the hormones abnormal?
It's not entirely clear why this happens. Many women who have anovulation also have a syndrome called polycystic ovary syndrome (PCOS). Its name comes from the fact that many women with PCOS develop multiple small cysts on their ovaries, although women can have PCOS without actually having cysts. In addition to infrequent menstruation, women with PCOS may be overweight, and may have unusual hair growth (on the chin or chest) and acne. About 5-10% of women have PCOS.

In PCOS, there is more estrogen than progesterone. In women who are overweight, the fat in the body converts some of the other body hormones to estrogen, and this leads to menstrual problems. When the women with PCOS lose weight, the PCOS sometimes gets better. However, PCOS can also exist in women who are not overweight, and in these women it is not clear why the hormones are abnormal.

There are reasons other than PCOS that a woman might not get her period. PCOS is most typical in women whose periods have always been irregular, rather than a new change. There are other causes or infrequent periods, like being underweight, thyroid disorder, high prolactin levels, kidney failure, breastfeeding, and certain medications, among others. It's important to be evaluated by a doctor to determine why your periods are irregular.

OK, my hormones don't work. But why is anovulation a problem? Isn't it lucky to not bleed every month?
When the endometrium is exposed to estrogen without the benefit of enough progesterone to match, it becomes very thick, and over many years, the cells in the endometrium can become abnormal, and eventually become cancerous.
Women who have untreated irregular periods for many years are at high risk of having endometrial (uterine) cancer. For that reason, it's important for women with irregular periods to see a gynecologist for evaluation. (There are other less common reasons why periods can be irregular, so it's important to have a full evaluation by a doctor.)

Can I get pregnant?
Women with anovulation often have infertility because they do not ovulate regularly. They may require medications like clomiphene citrate to provoke their ovaries to ovulate, and they may need to see an infertility specialist. However, it is impossible to know whether a woman is fertile before she tries to get pregnant.

What should I do about it?
In order to protect against cancer, women with anovulation or PCOS who are not actively trying to get pregnant should be on some form of hormonal birth control to balance out the estrogen and progesterone levels, and keep the uterine lining thin.
There are several forms of birth control that can protect against cancer.
The birth control pill is extremely effective. It contains estrogen and progesterone, and it replaces the body's production of those hormones. On the pill, level of hormones does not fluctuate over the month, which prevents ovulation, but the estrogen and progesterone are well matched, preventing cancer. Periods will become regular, monthly.
Ortho Evra, the contraceptive patch, and NuvaRing, the contraceptive vaginal ring, work very similarly to the pill, but are easier to use.
Depo provera, or the shot, is a large dose of progesterone that is given every 3 months. The progesterone provides a good match for the excess estrogen, and also prevents ovulation. Many women on depo provera do not menstruate, which is fine as long as the uterine lining is kept thin by the progesterone.
The Mirena IUD, which contains tiny amounts of progesterone, also provides a match for the excess estrogen in the body, and keeps the uterine lining thin. It lasts for 5 years.
The implant, which is now known as Nexplanon, is a small rod that is placed in the upper arm, and contains progesterone.
Women with anovulation or PCOS should talk to their doctor about which method is right for them.

In addition, aerobic exercise and weight loss in women with PCOS often helps improve hormonal function. Women with PCOS may also have diabetes or pre-diabetes, and may benefit from a diabetes medication called metformin. Evaluation by a doctor is the first step in determining whether infrequent periods are a sign of PCOS or another cause.

Here is more information about PCOS from womenshealth.gov