Implantation Bleeding vs. Your Period: How to Tell the Difference

Content medically reviewed by Caitlin Pandolfo, MD

If you are trying to get pregnant, you may be disheartened to see a little blood around the time your period is due. However, this does not always mean your period has started. That’s because implantation bleeding is common in early pregnancy. But how can you tell the difference?

“It can be difficult at first to know whether you have your period or whether it is a sign of pregnancy,” said Dr. Caitlin Pandolfo, OB/GYN at Essentia Health. “But if you know the signs to look for, it can be easier to distinguish implantation bleeding from your menstrual period or other issues that might require care.”

What Is Implantation Bleeding? 

Normally, a sperm fertilizes an egg in the fallopian tube, then moves to the uterus. Implantation, one of the first stages of pregnancy, occurs when a fertilized egg implants in the lining of the uterus. Implantation usually happens about seven to 10 days after your ovary releases an egg during ovulation.

The lining of the uterus is  made of a layer of tissue with small fragile blood vessels. When the fertilized egg implants in the uterine lining, it can cause these blood vessels to bleed. In contrast, period bleeding happens when your uterus sheds its lining as part of your regular menstrual cycle. It’s normal to have menstrual bleeding every month you are not pregnant until you reach menopause.

Is It Implantation Bleeding or Your Period?

“About one of every four pregnant women experiences implantation bleeding. When it occurs, women usually have not yet taken a pregnancy test or missed a period,” Pandolfo said. “This can make it tricky to tell what type of bleeding you are having. But some things like color and how long the bleeding lasts can be clues.”

Here are some ways to distinguish implantation bleeding from period bleeding –

• Color. Implantation blood is usually brown, dark brown, or pink, while period blood is bright or dark red.
• Flow. If the blood is light, spotty, or looks more like vaginal discharge, it could be implantation bleeding, which requires nothing more than a panty liner. If you are having heavy bleeding that soaks through pads or contains clots, it could be your period or another issue.
• Length. Implantation bleeding lasts anywhere from a few hours to a couple of days. For most people, menstrual periods last from three to seven days.
• Pain. You might have very mild cramps with implantation bleeding. During your period, cramps can range from mild to severe.

Will a Pregnancy Test Be Positive During Implantation Bleeding?

It’s usually too early to take a pregnancy test when you are having implantation bleeding. This is because home pregnancy tests work by checking for a hormone called human chorionic gonadotropin (HCG) in your urine. Your body begins producing HCG after implantation is complete.  If you test too early, there won't be enough HCG in your system to result in a positive test.

Even though a pregnancy test may not yet give accurate results, some women experience other signs of pregnancy while having implantation bleeding. These may include –

• Bloating
• Lack of energy
• Nausea
• Sore or tender breasts
• Headache

Having any of these symptoms can be additional signs that you could be pregnant.

Other Types of Bleeding During Pregnancy

Up to 25% of pregnant women experience bleeding during the first trimester of pregnancy. In addition to implantation bleeding, another reason you could bleed lightly during early pregnancy is having a friable cervix, which means your cervix bleeds more easily due to the development of blood vessels. This can cause bleeding after sex or after having a pelvic exam. Bleeding from implantation or a friable cervix are not causes for concern.

However, there are other serious causes for bleeding to occur in early pregnancy, such as –

• Ectopic pregnancy. This means a fertilized egg has implanted outside of the uterus, usually a fallopian tube. This can be a life-threatening emergency. Abnormal vaginal bleeding, low back pain, and pain in the pelvis or abdomen are symptoms.
• Early pregnancy loss. Also called miscarriage, pregnancy loss before 20 weeks happens in about 10%–25% of pregnancies. Symptoms include cramping and abnormal bleeding. It’s important to note that having implantation bleeding does not always mean you will have a viable pregnancy, as pregnancy loss could still occur.
• Infection. Certain types of infections during pregnancy can cause bleeding, such as some sexually transmitted infections.
• Molar pregnancy. This happens when an egg joins incorrectly with sperm, resulting in a benign tumor that resembles a bunch of water-filled sacs.

Later in pregnancy, other issues can cause bleeding, such as problems with the placenta. Heavy bleeding can signal problems such as placenta previa, which means the placenta is partly or completely covering the cervix. Placental abruption, when the placenta partially separates away from the uterus, and placenta accreta, when the placenta attaches to the uterine wall too deeply, are other possible causes of heavy bleeding. Depending on the severity, these issues can sometimes cause serious complications.

When to See Your Provider

Implantation bleeding is not dangerous. If your bleeding is light and lasts less than a few days, you usually don’t need to see your provider.

“If you experience heavy bleeding or have clotting along with pain or cramping and suspect you may be pregnant, contact your provider. They help determine if you have your period, implantation bleeding, or another issue,” Pandolfo said. “It’s also a good idea to see your provider if you have any bleeding or other symptoms that concern you. We’re here to help you with any questions and assist through every stage of pregnancy.”