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

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. This results in implantation bleeding, which might 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 women who are on birth control pills or have polycystic ovary syndrome (PCOS). 

The only surefire way to tell the difference is taking a pregnancy test. "Women 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. Here, experts share what you need to know .

menstrual leave
Credit: 9nong/Shutterstock 

Is It Implantation Bleeding or Period Spotting?

Some experts claim spotting that starts off 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 what implantation bleeding looks like. "There's no way to tell the difference between intermenstrual bleeding and implantation bleeding just by looking," he says. 

If you want to determine whether you have implantation bleeding or your period, you should pay attention to the following three symptoms 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 woman 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. It's important to pay attention to what feels out of the ordinary for your body.

Symptom #2: Flow

"Some women 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 woman may feel like her 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. Blood flow that's more consistent—starting off light and getting heavier as the days progress—is likely a menstrual cycle.

Should I Take a Pregnancy Test If I'm Spotting?

Any woman 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.

Keep in mind that implantation bleeding always happens before a missed period. If you experience heavy 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, a common phenomenon that occurs in 15 to 25 percent of women 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.

Women who experience abnormal first trimester bleeding should see their OB-GYN or visit an emergency center immediately. "There are pregnancies that bleed early on that do just fine," says Dr. Patounakis, "but your healthcare provider needs to evaluate to make sure you're safe."