Implantation Bleeding or Your Period? How To Tell the Difference

What does implantation vs period bleeding look like? Experts explain how to tell if your spotting is an early sign of pregnancy or your monthly menstrual cycle.

Medically reviewed by Kiarra King, M.D.

When a fertilized egg implants in the uterus, which usually happens 10 to 14 days after conception, it sometimes causes part of the uterine lining to shed. When this occurs, it results in implantation bleeding, which can be one of the earliest signs of pregnancy.

But here's the frustrating part: The blood that's released is nearly indistinguishable from normal spotting or breakthrough bleeding that can occur mid-cycle—especially in people who are on birth control pills or have polycystic ovary syndrome (PCOS).

Unfortunately, knowing what spotting looks like doesn't usually help you distinguish it from implantation bleeding. So, how do you know if what you're seeing is implantation bleeding vs period bleeding?

The only surefire way to tell the difference is to take a pregnancy test. "People are so anxious about knowing whether or not they're pregnant, they want to have definitive signs to look for, but unfortunately, only time will tell," says Anuja Vyas, M.D., FACOG, with Houston Methodist Obstetrics and Gynecology Associates.

That said, certain symptoms can offer hints that you could be experiencing implantation bleeding rather than period-related spotting. Here, experts share what you need to know.

What Is Implantation Bleeding?

After a fertilized egg implants in the uterus, it can sometimes cause shedding of the uterine lining. This leads to implantation bleeding, which can be one of the earliest signs of pregnancy.

Related: Can You Notice Signs of Implantation After Conceiving?

Implantation Bleeding vs Period Symptoms

Spotting usually means just a few, well, spots of blood on your underwear or toilet tissue. Some experts claim spotting that starts brown or wine-colored and becomes a brighter red is most likely the start of your period. But George Patounakis, M.D., Ph.D., FACOG, a fertility specialist in Florida, says Googling pictures won't help if you're wondering if your bleeding is due to implantation. "There's no way to tell the difference between intermenstrual bleeding and implantation bleeding just by looking," he says.

To determine whether you have implantation bleeding or your period, you should pay attention to the following three symptoms and characteristics instead.

Symptom #1: Cramping

Dr. Vyas says that cramping associated with implantation, while sometimes intense, doesn't typically last as long as it would during a menstrual cycle. But Dr. Patounakis cautions that each person experiences uterine contractions differently. "A little blood inside your uterus can cause severe cramps in some women and no cramps in other women," he says. Therefore, paying attention to what feels out of the ordinary for your body is important.

Symptom #2: Flow

"Some people experience implantation bleeding as heavy as the first day of their menstrual cycle, but it typically only lasts a couple of days," says Jay M. Berman, M.D., FACOG, chief of gynecological services at Detroit Medical Center's Harper Hutzel Hospital and professor of obstetrics and gynecology at Wayne State University. "When it ends, the person may feel like their period is about to start or might have breast tenderness or some nausea and may even start to feel pregnant."

Symptom #3: Consistency

Implantation bleeding can be off-and-on for a couple of days, similar to spotting, and does not produce the same amount of blood as menstruating. More consistent blood flow—starting light and getting heavier as the days progress—is likely a menstrual cycle.

Related: Everything You Need to Know About Implantation Cramps

Will a Pregnancy Test Be Positive During Implantation Bleeding?

Keep in mind that implantation bleeding will happen before a missed period. Pregnancy tests are more likely to be accurate if they are taken after a missed period. You may get a false negative if you test too early.

But anyone who's been sexually active in the previous month and could possibly be pregnant should take a pregnancy test after irregular bleeding of any kind, says Dr. Vyas.

Other Causes of Bleeding

If you experience bleeding that isn't implantation—or period-related (after a positive pregnancy test, for example), it could be what's known as first-trimester bleeding.

According to the American College of Obstetricians and Gynecologists (ACOG), implantation bleeding is a common phenomenon that occurs in 15% to 25% of people early in their pregnancy. "But it might also be the first sign of a pregnancy loss or even an ectopic pregnancy," a potentially fatal condition where the embryo implants outside of the uterus, says Dr. Berman.

Other causes for spotting or bleeding can include:

• Ovulation bleeding: Ovulation bleeding happens in around 5% of menstruating people and is thought to be caused by hormonal changes.

• Early miscarriage: Miscarriage bleeding can appear pink, bright red, or brown and may include clotting. It can begin as spotting and become heavier and could include uterine cramps.

• Ectopic pregnancy: Ectopic pregnancy happens when a fertilized egg implants somewhere outside of the uterus, such as a fallopian tube, or attaches to an abnormal part of the uterus, such as scarred tissue.

• Bacterial Vaginosis (BV): Research has long shown that bleeding in early pregnancy can be caused by bacterial vaginosis or other lower genital tract infections, which can lead to preterm birth. Since BV poses a risk to the fetus, it is common practice to screen pregnant people for the infection.

• Polycystic ovary syndrome (PCOS): PCOS is a reproductive hormone imbalance that affects menstruation cycles and can cause abnormal uterine bleeding.

• Oral contraceptives: Oral contraceptives are 99% effective if used perfectly, according to Planned Parenthood. Additionally, research has shown that missing or skipping oral contraceptives can lead to irregular bleeding.

Those who experience abnormal first-trimester bleeding should see a health care provider. "There are pregnancies that bleed early on that do just fine," says Dr. Patounakis, "but your health care provider needs to evaluate to make sure you're safe."

Key Takeaway

Implantation bleeding is a common phenomenon that occurs in up to 25% of pregnant people. Since the spotting occurs early in pregnancy, it can be difficult to know if it is implantation bleeding vs period bleeding—the best way to know what type of bleeding you're experiencing is to talk to your doctor.

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