Ob-Gyns Explain What Common Period Blood Colors Actually Mean

Periods can be unpredictable, and period blood is no different. Although it's normal for period blood colors to range from light pink to dark black, it may feel unsettling to see a different shade — especially when you don't know what's causing the change. While some period blood colors may be indicative of a bigger issue, the good news is there's a much wider variety of period blood colors that generally aren't cause for concern. If you've ever wondered what the color of your period blood means, we broke down the entire rainbow with ob-gyns.

As board-certified ob-gyn Janelle Mary Jackman, MD, FACOG explains, period blood colors are at least partially affected by the timing of discharge and a process called oxidation. "The color of period blood is really determined by how long the blood has remained in your uterus and vagina," Dr. Jackman tells POPSUGAR. "It gets darker due to the oxidization of blood — the longer it stays around before it is discharged."

In some cases, period blood colors can be indicative of other things going on in your body, such as an infection, low estrogen, or ovulation. The duration, flow, and color varies depending on individual circumstances, but ob-gyn Kendra Segura, MD, MPH, FACOG, explains that periods will often start out pink on the first day, then turn bright red for a few days, followed by dark red on the heaviest day, and, finally, brown or black for the remaining day or two.

While it's normal to experience some variety in your period blood colors, pay attention to any sudden or unfamiliar changes. Gray and off-white period blood colors are typically a sign to speak to a healthcare provider (but more on that below). Also, if you're experiencing other unusual symptoms during or around your menstrual cycle (including severe cramping, spotting between periods, larger blood clots), that's also worth mentioning, per the Cleveland Clinic. Read on for a full breakdown of every period blood color and what each one says about your health.

"Pink blood is usually present at the onset of menses as fresh blood mixes with vaginal mucus and discharge, making it a lighter hue," Dr. Jackman says. Additionally, if you have a lighter flow, you may see pink blood throughout your period simply because the blood isn't shedding as quickly or as steadily.

Thin, pink period blood may also be a sign of low estrogen or a hormonal imbalance (especially if you're bleeding between periods, aka spotting). Implantation bleeding, or light bleeding within the first few days of conception, can be light pink, per the American Pregnancy Association, as well as postpartum bleeding (called lochia).

If you're already pregnant, pink blood may also be a sign of pregnancy loss, so it's imperative to reach out to your doctor right away. Other symptoms of pregnancy loss include cramping, passing tissue, abdominal pain, and dizziness.

Like that pink hue, bright red blood is typically seen toward the beginning of your period, when the blood is freshest. "As one's uterus contracts and the flow gets steadier, the blood sheds quicker as the cycle continues," Dr. Jackman explains. "This makes the blood a more crimson red as it does not oxidize due to quick explosion." In this case, "explosion" refers to the faster rate at which the blood leaves the uterus and vagina.

Bright red blood may also be caused by pregnancy loss as well as uterine polyps or fibroids, which are noncancerous growths in the uterus that can cause the kind of heavy flow that leads to bright red period blood. Adenomyosis, which is when the tissue that lines your uterus grows into and thickens your muscle tissue, may also cause heavy, painful periods with bright red blood, along with pelvic pain and pain during sex.

Blood that's a darker shade of red is older than the bright red blood seen toward the beginning of your period. While blood will typically grow darker as your cycle progresses, it can also appear darker if it's been "sitting in your uterus" for some time, according to Dr. Segura. Dark red blood is most often seen in the morning or after you've been laying down for a while — because the longer it takes for the blood to pass through the uterus, the more time it has to oxidize. Dr. Segura notes that dark red blood could also be an indication of a passing blood clot, which is similar in color. If you have a heavier flow, you may also see more dark red blood compared to those with lighter periods.

Brown period blood is usually seen at the very end of your period, just before before the bleeding stops completely. "The blood can look extremely dark — brown or even black — if it has taken longer to exit the vagina," Dr. Jackman says. "This is blood that has had a lot of time to oxidize; thus, its dark appearance." Dr. Segura adds that, if you notice brown discharge at the beginning of your period, it's likely just blood that was left over from the previous cycle. No need to be concerned. Implantation bleeding can also be a dark brown, rust color, but it's not a surefire sign of early pregnancy. If you also experience mild cramping, nausea, breast tenderness, and/or headaches, you may want to make an appointment with your ob-gyn.

Think of black discharge as your period's finish line. "Although this may look alarming, it isn't a reason to panic," Dr. Segura explains. "Red blood that turns black means that the blood has been oxidized. Hence, it's been in your uterus for awhile and we call it 'old blood.'" Again, this will usually occur at the end of your period, when your flow has slowed down significantly.

Black blood can also occur when you have an object stuck in your vagina (think: a tampon, sex toy, menstrual cup, condom, etc.), which can irritate the lining and cause an infection. Symptoms of the infection could include black discharge, fever, a bad smell, or itching or a rash in your vagina and on your vulva. Pelvic inflammatory disease and sexually transmitted infections (STIs), particularly gonorrhea and chlamydia, can also lead to black discharge as well as pain, itching or burning while urinating. You may also experience black bleeding as a sign of a missed pregnancy loss (when the fetus stops developing but doesn't pass out of your body for four weeks or longer) or lochia.

Orange period blood can be more indicative of an infection. Although it may just be the result of cervical mucus mixing with your normal period blood, watch out for symptoms like vaginal itching, abnormal discharge, and any unusual odors. If you're experiencing orange period blood, you may want to contact your doctor just to be safe.

If your period discharge shows up gray or off-white, the USA Fibroid Center recommends seeing a doctor right away. It may be a symptom of infection, such as bacterial vaginosis, so keep an eye out for other symptoms, such as itching, a bad smell, fever, or pain. Gray discharge can also be a sign of pregnancy loss.