Implantation bleeding is an early sign of pregnancy that occurs when a fertilized egg (embryo) implants into the wall of a person’s uterus. It can cause light bleeding that lasts up to two days. Implantation bleeding is considered a normal part of pregnancy.
Implantation bleeding occurs when a fertilized egg implants into the lining of your uterus (endometrium) during conception. After sperm fertilizes the egg, it’s called an embryo. The embryo travels down the fallopian tubes into your uterus. At this point in your menstrual cycle, the endometrium is thick and vascular. This makes it an ideal spot for the developing embryo to attach and grow. Implantation can disrupt the blood vessels in the lining of your uterus — this is the blood you see during implantation bleeding.
Not everyone will experience implantation bleeding. It’s considered a normal part of pregnancy and isn’t usually a cause for concern.
Implantation bleeding is often confused with your menstrual period. It can happen when your period would’ve been due to arrive. The exact time varies, but most implantation bleeding occurs about six to 12 days after the egg is fertilized. In most cases, people haven’t taken a pregnancy test yet and don’t know they’re pregnant.
About 25% of pregnant people will experience implantation bleeding. It’s considered a normal part of pregnancy.
Implantation bleeding is very light. This is called spotting. Some people will have implantation bleeding over the course of a few days while others will only bleed once. Most of the time, you’ll see it as a spot in your underwear or on toilet paper while wiping. Heavy bleeding isn’t typical for implantation bleeding and could be a sign of an underlying issue.
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Implantation occurs when a fertilized egg attaches to the lining of your uterus. Your uterine lining is filled with blood vessels and vascular tissue. As the embryo embeds into that lining, light bleeding can occur.
Think of it like a small animal digging around in the dirt to find a cozy place to sleep. The animal will burrow and dig into the ground so much that dirt will get displaced. When implantation bleeding occurs, the lining of your uterus is like dirt, and your embryo is like a small animal trying to get comfy.
Once implantation is complete, the pregnancy continues to develop, and your uterus begins to produce a hormone called human chorionic gonadotropin (HCG). This hormone is responsible for keeping the uterine lining thick (helping the embryo stay in place) and it gives you a positive pregnancy test.
Implantation bleeding is often one of the first signs of pregnancy. The main symptom is light bleeding or spotting that lasts a day or two. Sometimes it’s accompanied by other early pregnancy symptoms such as:
Implantation bleeding is brown, dark brown or slightly pink. It’s considered spotting or light bleeding. It shouldn’t be heavy enough to soak through a pad. Implantation bleeding resembles the flow of vaginal discharge more than it resembles the flow of your period. If your blood is bright red or contains clots, it might indicate your menstrual period or another issue.
Implantation bleeding can last a few hours or a few days. The length of time you have implantation bleeding varies. It’s rare for it to last more than three days.
There are several differences between period blood and implantation bleeding.
There’s no treatment to stop or decrease implantation bleeding since it goes away on its own in a healthy pregnancy. In most cases, wearing a panty liner in your underwear is all you’ll need. If your bleeding is soaking through a pad, it’s probably not implantation bleeding.
There aren’t any complications of implantation bleeding. It’s considered a normal part of pregnancy. As long as the bleeding is light, lasts a day or two and isn’t accompanied by cramping or pain, there are no complications associated with implantation bleeding.
Vaginal bleeding and bleeding during pregnancy are pretty common. In some cases, it can indicate a serious condition, but other times it’s considered normal.
Some causes of bleeding during early pregnancy are:
Some causes of vaginal bleeding not related to pregnancy are:
Implantation bleeding doesn’t harm you or the fetus. If your bleeding is light and not accompanied by pain, there’s usually nothing to worry about. Call your healthcare provider if you experience heavy bleeding, clotting, pelvic pain or cramping, as it might be a sign of a problem.
Your body doesn’t release the hormone HCG until after implantation is complete. An at-home pregnancy test checks for a certain level of HCG in your urine. If you take a pregnancy test too soon, it might give a negative result when you might actually be pregnant (false negative). You may want to wait until your implantation bleeding has stopped and you’re sure you have a missed period. However, your healthcare provider can order a blood pregnancy test for you if you’re unsure. A blood test detects HCG much sooner than urine can.
A note from Cleveland Clinic
Implantation bleeding is a common and normal sign of early pregnancy. Call your healthcare provider if you’re unsure if your bleeding is implantation bleeding or something else. They’ll be able to explain the signs to you and advise if further treatment is necessary.
Last reviewed by a Cleveland Clinic medical professional on 12/16/2022.
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