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The Modern guide to vaginal bleeding

The Modern guide to vaginal bleeding

11 min read

Vaginal bleeding isn’t always blood that comes from your vagina — well, not really.

According to Dr. Eva Luo, MD, MBA, an OB-GYN and medical advisor to Modern Fertility, “What’s often called ‘vaginal bleeding’ could be coming from anywhere — the uterus, cervix, or even the rectum."

In many cases, though, all we see is blood down there. So, what’s considered normal? What's important to watch out for? We’ll cover the different types of vaginal bleeding, causes of abnormal bleeding, and when to call your doc.

Keep in mind that your vulvovaginal area is unique, so what’s typical for your body may not be the same as someone else’s typical.

Bleeding during your period

Vaginal bleeding happens primarily because of your period. Three aspects of your period to keep an eye on include flow, frequency, and color.

Period flow

The flow of your period can fluctuate throughout your cycle. This American Journal of Epidemiology study that looked at the menstrual cycles of 201 women found that menstrual bleeding generally lasted five days (though, as we’ll cover a bit later, there are differing opinions on what period lengths are considered “normal”), and three of those days included heavier bleeding.

Here’s another way to think about it: A few heavy flow days during a menstrual period is natural, but if you're bleeding through multiple pads within a two-hour frame, it’s important to schedule an appointment with a healthcare provider.

When it comes to extremely heavy bleeding during your period (also known as “menorrhagia”), here are some symptoms to watch out for and discuss with your doctor. These could be caused by issues related to the uterus or cervix (like fibroids or polyps, uterine or cervical cancer), hormones, or other disorders:

  • Soaking through multiple menstrual products within two hours
  • Seeing blood clots larger than a quarter
  • Symptoms suggestive of anemia (fatigue, dizziness, racing heart, shortness of breath)
  • Constant pain in your lower stomach
  • Menstrual bleed that lasts longer than seven days
  • Inability to go about your normal day

One thing to mention is that clots, medically, aren’t usually a big deal. “Depending on the position your body is in, the blood pools in the vagina. And eventually that blood will clot," says Dr. Luo. As she explains it, it’s similar to how a cut on your hand would eventually clot and stop bleeding over time.

Period frequency

While most of us are taught that the menstrual cycle lasts for 28 days on average, there’s a window of what’s considered “normal” — and leading medical bodies have differing ideas of what that window is.

The American College of Obstetricians and Gynecologists (ACOG) and the US Office of Women’s Health (OWH) say that cycles can last anywhere from 24-38 days, but the Mayo Clinic says 21-35 days. Having a 31-day cycle every month instead of the textbook 28-day cycle doesn’t alone indicate any issues, but if your cycle length starts changing and moves out of “normal” range, that’s something to bring up with your doctor. Your normal is what’s key here.

These same organizations have different takes on what’s “normal” when it comes to the number of days you bleed during your cycle — meaning the length of your actual period. ACOG says it typically lasts "up to 8 days," according to ACOG, OWH says 4-8 days, and the Mayo Clinic says 2-7 days.

If you don’t get periods by age 16 or don’t get a period for more than three months, that’s called amenorrhea. If you have fewer than 10 periods a year, that’s called oligomenorrhea. It’s best to check with your healthcare provider if you experience either of these.

Period color

Dark reds, bright reds, and browns are all considered “normal” in terms of period blood color. Blood changes color if it’s exposed to air oxygenation for a period of time. Blood color will appear slightly darker once it’s reacted with oxygen and become more concentrated. At different points of your period, blood may take longer to leave your body — and in those cases, blood will appear darker red or brownish.

A major influence in the color of your period blood is the birth control you’re on. Birth control changes our hormones throughout our cycle, as Dr. Luo says. This is why people with hormonal IUDs tend to see darker red or brown blood — older blood comes out during menstruation because the lining has become so thin. However, explains Dr. Luo, this isn’t the case for copper IUDs that don’t change our hormones. The copper ions that copper IUDs release into our bodies can cause longer and heavier periods, but they have little to do with the color of your menstrual blood.

If the color of your vaginal blood isn't part of the red color spectrum, and appears either grayish or light pink and watery, then that's no longer considered natural and is something you should mention to your doc.

Potential causes of abnormal vaginal bleeding (or discharge)

  • Endometriosis
  • Bleeding disorders
  • Endometrial, cervical, or tubal cancer
  • Cervicitis (inflammation of the cervix)
  • Endometritis (inflammation of the uterus) or other pelvic infections
  • Bleeding or spotting between periods
  • Bleeding or spotting after sex
  • Heavy bleeding during your period
  • Menstrual cycles longer than 38 days or shorter than 24 days
  • Periods varying by more than 7–9 days
  • Pelvic exam (bleeding up to one month after surgery)
  • Cervical biopsy
  • Endometrial biopsy

Bleeding in between periods (aka spotting)

Vaginal bleeding, usually light, that happens outside of your period is considered spotting — also known as intermenstrual bleeding or metrorrhagia.

Intermenstrual bleeding can be caused by ovulation bleeding, which happens during ovulation — when the ovary releases an egg for possible fertilization. “Ovulation sounds like this wonderful, magical thing that happens,” Dr. Luo explains, but at the same time, “your ovary is truly exploding and something is being released and it has to repair itself.” The combination of that trauma and the spike in hormones can both trigger inflammation and spotting.

According to Dr. Luo, additional causes for intermenstrual bleeding include uterine polyps and cervical friability (sensitivity). If you regularly experience bleeding between periods, make note of when this occurs (i.e., after sex, in the middle of your cycle, etc.) and discuss this with your healthcare provider.

Bleeding while on birth control

The two main reasons you may experience bleeding while on birth control include withdrawal bleeding and breakthrough bleeding. They both are caused by changes in your hormones.

Determining the type of vaginal bleeding you experience while on birth control depends on how your birth control impacts ovulation. Since combined oral contraceptives (the pill), patch, vaginal ring, implant, and injectable can all affect ovulation, bleeding that occurs while taking any of those methods will technically be “withdrawal” bleeding (more on this in a bit).

Most people who use lower-dose hormonal IUDs (Mirena and Liletta) will have lighter and/or shorter periods due to thinning of the uterus lining, but many will have no periods at all. Some people who take the minipill (progestin-only) or low-dose (Kyleena and Skyla) hormonal IUDs won’t see their ovulation or timing of periods impacted.

“The biggest thing to emphasize for Mirena, Liletta, Skyla, and Kyleena,” adds Dr. Luo, “is that you may still be ovulating even though your bleeding is different than possibly your baseline.” The only birth control options that won’t change your menstrual cycle at all are nonhormonal, like condoms and copper IUDs.

Withdrawal bleeding

Withdrawal bleeding is the body’s response to hormonal changes — specifically progesterone. It happens when you remove certain birth control methods (like the vaginal ring) or during the placebo week of the pill. During this transition period, the body adjusts to the drop in hormones.

While some people with uteruses prefer to bleed while taking the pill, withdrawal bleeding isn’t the same as a regular period. That’s because “natural” periods are caused by a sudden drop in progesterone after the corpus luteum (which is what the ruptured ovarian follicle turns into after ovulation) dies, triggering the shedding of the uterus lining. Though withdrawal bleeding doesn’t qualify as a “natural” period, it will often seem pretty similar visually. If withdrawal bleeding does appear different from your periods, Dr. Luo says it’ll likely be lighter because hormonal birth control (mainly the progesterone component) thins the uterus lining.

But withdrawal bleeding while on hormonal birth control isn’t necessary to be healthy. You can skip withdrawal bleeding by only taking the active birth control pills instead of switching between active and placebo. Talk with your healthcare provider if this is something you’d like to do.

Breakthrough bleeding

Breakthrough bleeding is a side effect of birth control methods like the pill, patch, IUD, implant, and ring as the body adjusts to the hormone levels. It generally resolves itself within a few months. But with continuous-dose pills and the implant, breakthrough bleeding can occur more frequently.

Why does breakthrough bleeding happen? According to Dr. Luo, breakthrough bleeding is the result of the uterus lining becoming so thin that it’s unstable — likely due to a combination of progesterone’s effect of thinning the lining and lower or no estrogen levels in the hormonal birth control.

Bleeding during pregnancy

15%-25% of pregnant people experience bleeding during the first trimester. “Bleeding can happen during the first trimester and can be for a variety of reasons,” says Dr. Luo. Some instances of vaginal bleeding early on in pregnancy, like implantation bleeding, are natural and don't harm the baby. Other instances of vaginal bleeding during pregnancy can signal miscarriage or ectopic pregnancy, which is why it’s so important to discuss with your doctor any type of bleeding that occurs before 13 weeks.

Implantation bleeding

Implantation bleeding can happen about 1-2 weeks after fertilization, when a fertilized egg attaches to the uterus lining. As the fertilized egg digs itself into the uterus lining, a few blood vessels may break and cause bleeding.

Since implantation bleeding is speculated to start around the same time you would have your regular menstrual cycle, it may be confused with a period. But implantation bleeding is lighter bleeding and goes away without intervention. Some people may not notice it at all.

 Menstrual bleeding:

  • Average to heavy bleeding
  • Bright to dark red in color
  • Clotting present in heavier flows
  • Requires intervention of menstrual products

 Implantation bleeding:

  • Light bleeding
  • Light pink to pink in color
  • No clots
  • No treatment required

Implantation bleeding is natural — but bleeding in any amount during pregnancy should be looked into by a healthcare provider.

Subchorionic hematoma

Another possible cause of bleeding during pregnancy is called a subchorionic hematoma. This type of bleeding occurs when the chorion (a double-layer membrane around the fetus that becomes the placenta) partially separates from the uterine wall. The bleeding from a subchorionic hematoma typically appears as dark brown, similar to chocolate.

While Dr. Luo says this type of bleeding is usually benign, it’s sometimes associated with increased risk of miscarriage. More than anything else, she explains, a subchorionic hematoma can be frustrating because the source of bleeding isn’t immediately clear and it leads to additional evaluations throughout pregnancy.

Abnormal instances of vaginal bleeding during early pregnancy

Ectopic pregnancy
An ectopic pregnancy happens when an egg gets fertilized outside of the uterus — in the fallopian tubes, for example. As the pregnancy grows, the fallopian tube is at risk of exploding, which can cause internal bleeding that’s life threatening. Ectopic pregnancies are rare, happening in 2 out of every 100 pregnancies.

Vaginal bleeding and pain are two indicators of an ectopic pregnancy, so it’s important to call your healthcare provider immediately if you’re experiencing these symptoms. If you’re not feeling well, do not hesitate to go to an emergency room and call your doctor on the way.

A pregnancy is more likely to be ectopic if you get pregnant after permanent sterilization (i.e., tubal ligation, removal of the fallopian tubes) or implanting an IUD. However, keep in mind that the likelihood of pregnancy after sterilization or with an IUD in place is <1%.

Early pregnancy loss
Early pregnancy loss usually occurs within the first 13 weeks of pregnancy and happens in about 10% of all clinically recognized pregnancies, though the number is likely as high as 20% for all pregnancies.

Dr. Luo says, “Miscarriages tend to be heavier bleeding — often more than a period — but it depends on how far along you are.” This means that the amount of vaginal bleeding you experience after a miscarriage at five weeks will likely be less than the amount you experience after a miscarriage at 10 weeks.

Call your doctor if you experience any bleeding during early pregnancy. If the bleeding is so heavy that you’re soaking an entire pad within an hour and it’s not stopping, call your doctor immediately.

Bleeding during late pregnancy
An important sign of preterm labor, which is labor that begins before 37 weeks of pregnancy, is vaginal bleeding. Since not all vaginal bleeding during pregnancy appears as heavy or comes from the same source, Dr. Luo suggests keeping an eye out for vaginal bleeding “in combination with other signs like leakage of fluid or painful contractions." Lighter bleeding on its own may be a sign of inflammation or growths on the cervix.

Heavier bleeding could be a sign of preterm labor as well as one of the following issues with the placenta:

  • Placental abruption: When the placenta partially (or completely) separates from the inner wall of the uterus. This can disrupt the flow of oxygen for the infant during delivery.
  • Placenta previa: When the placenta partially (or completely) covers the cervix. This can cause severe bleeding during both pregnancy and delivery.
  • Placenta accreta: When the placenta grows too deeply into the inner wall of the uterus. This causes severe bleeding after delivery because the placenta doesn’t detach. It can also invade the muscles of the uterus.

These conditions are typically identified and diagnosed during routine ultrasounds. So, most patients who will experience one of these conditions have been given counseling that bleeding may occur and what to do if it does. Still, it’s hard to know exactly where blood might be coming from when you experience vaginal bleeding — and bleeding late in pregnancy, regardless of the cause, could potentially be a sign of either preterm or normal-term labor. If you have any bleeding during pregnancy, it’s important to get checked out with your healthcare provider.

Bleeding during perimenopause

Perimenopause is the period of time before menopause when your hormones and menstrual cycle start to change. The ovaries get smaller and stop producing as much estrogen. As a result, your periods can become irregular.

As far as vaginal bleeding goes, your periods may look different. It can be lighter or heavier, depending on what a regular period for you looks like. It’s also completely natural to see some irregularity (like skipping a period or two) during perimenopause.

Menopause marks the time when your menstrual cycle comes to a complete stop — defined by an entire year of no bleeding. Until then, menstrual bleeding in various shapes and forms is totally natural. If you experience any bleeding after an entire year of no bleeding, talk to your healthcare provider about doing an evaluation. While the most likely cause is vaginal dryness (resulting from decreased estrogen), an evaluation is necessary to rule out other possibilities.

Potentially abnormal instances of vaginal bleeding during or after perimenopause:

  • Underactive thyroid
  • Vaginal dryness aka vaginal atrophy
  • Cancer

When to call the doc about vaginal bleeding

It’s hard to know for sure if vaginal bleeding is abnormal until a proper exam is done. Although different doctors have varying thresholds for concern when it comes to vaginal bleeding, Dr. Luo says it’s still important to connect with yours if you notice any vaginal bleeding that feels different or off. “The reason you should reach out to your doctor is because if it becomes more serious — if there’s more bleeding, if you’re cramping — you’re plugged in and the doc knows that they need to watch you carefully,” she explains.

When bleeding can come from many different places for different reasons and your only source of information is your tampon or pantyliner, it's tough to tell exactly what’s going on. Your healthcare provider can help you sort through your vaginal bleeding quandary. Try to get them involved as early as possible.

This article was medically reviewed by Dr. Eva Marie Luo, an OB-GYN at Beth Israel Deaconess Medical Center and a Health Policy and Management Fellow at Harvard Medical Faculty Physicians, the physicians organization affiliated with the Beth Israel-Lahey Health System.

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Alex Shea

Alex is a sexual wellness and relationship writer who has a love for sparking deep conversations about the awkward and uncomfortable topics in life.

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