Implantation bleeding occurs when a fertilized egg attaches to the lining of a female’s uterus to start the growth process of pregnancy.

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It is a common occurrence in pregnant females, yet many are completely unaware of what it is.

Some people may confuse the bleeding with spotting with menstruation, as the two can appear similar.

However, this bleeding is very light and usually requires no medical attention. In some cases, however, implantation bleeding may require a visit to a healthcare practitioner.

Implantation bleeding happens just before the expected menstrual cycle. It is a very early sign of pregnancy, occurring a few days before a pregnancy test will confirm a female is pregnant.

The process of implantation starts with fertilization. Once sperm has fertilized an egg, it is called an embryo.

The embryo travels through the fallopian tube toward the uterus. During this time, the embryo multiplies, becoming a blastocyst, which is a number of cells bunched together.

Once the blastocyst reaches the uterus, it will look for a good spot to attach itself to the wall of the uterus. This attachment to the uterus is called implantation. Once implantation is complete, the embryo will begin its 9-month journey to becoming a newborn.

Implantation usually occurs about 1-2 weeks after the egg has been fertilized. This is also around a week after ovulation and a few days before a female has her regular period.

While implantation happens, the attachment of the embryo to the uterine wall can break down some of the blood vessels in the area, causing some mild bleeding.

Implantation bleeding is one of the earliest identifiable signs of pregnancy.

There are some distinct signs and symptoms to help a person identify implantation bleeding:

  • Early bleeding: Implantation bleeding will often occur a few days before the expected menstruation cycle. This is not always the case, however, and many people confuse the two.
  • Unusual colored discharge: Implantation bleeding produces an unusual discharge that varies in color from pinkish to very dark brown or black.
  • Very light bleeding: Bleeding and discharge caused by implantation is light. Many people experience just a few hours of spotting, one spot, or just a streak of discharge.
  • Cramping: Implantation can also cause mild and temporary cramps.

Other signs

As implantation is an early sign of pregnancy, a person may also experience other pregnancy-related symptoms. Early signs of pregnancy can vary from person to person and may include:

  • mood swings
  • tiredness
  • dizziness
  • headaches
  • tender, swollen breasts
  • nausea and vomiting
  • constipation
  • increased sense of smell
  • food cravings and aversions
  • a raised body temperature

However, not everyone will experience the symptoms above. In some people, the only symptom may be some light spotting lasting just one day.

Implantation bleeding is a typical sign of pregnancy and is not usually dangerous. Because of this, there is no need for treatment.

Bleeding caused by implantation usually clears up within a couple of days with no treatment necessary. Heavy bleeding may be a sign of menstruation or a pregnancy complication. Doctors recommend that a person does not use tampons during this time.

A person should speak with their doctor if they are experiencing bleeding and think they may be pregnant.

Many females confuse implantation bleeding with a light menstrual cycle. There are a few steps a person can take to help them identify what is happening:

Inspect the blood

First, the blood itself can provide some answers. Implantation bleeding will usually look different from menstrual bleeding. It may be darker than period blood due to the extra time it takes for the blood to travel through the vagina.

The amount of bleeding is usually very light as well. In some cases, females may experience a few hours of spotting and nothing more. Some people may experience a single spot of blood and discharge with no other signs. It will often produce a discharge with a pink or brownish tint.

Menstruation usually produces blood with more of a red color that lasts a few days or more, with discharge ranging from heavy to light during that time.

Most people understand what their typical blood flow looks like and would likely notice that implantation bleeding looks different.

Check the timing

Any person who suspects that they are experiencing implantation bleeding should think of the timing since they last had sex.

Implantation occurs around 1-2 weeks after fertilization. This puts it near or just before the time of menstruation in most cases. If it has been more than a month since a female has had sex, they are unlikely to be experiencing implantation bleeding.

The easiest way to find out is to wait a few days and then take a home pregnancy test. These tests work best a few days after implantation bleeding has stopped.

“Sex” means different things to different people and in different circumstances. For the purposes of this article, we use the term to refer to sexual intercourse that involves the ejaculation of semen into a vagina.

Check for other symptoms

Associated pregnancy symptoms may also help a person identify the difference between implantation bleeding and menstruation.

One easily identifiable symptom is morning sickness. A feeling of nausea first thing in the morning may be a sign of pregnancy and is usually not a sign of regular menstruation. This nausea may also occur as a result of certain everyday smells, such as meat, garlic, or pets.

Another symptom caused by implantation is cramping, which occurs as the egg attaches to the wall of the uterus. These cramps are often very light compared with those that many females experience during a regular period.

Tenderness in the breasts may also be a sign of pregnancy, especially in females who do not experience breast soreness during menstruation.

Other symptoms may be harder to gauge, such as mood swings and food cravings. These can be a sign of both pregnancy and premenstrual syndrome (PMS).

Learn more about the early signs of pregnancy.

Implantation bleeding is not a cause for concern most of the time. It is a sign that the embryo has attached to the uterine wall and is starting to grow.

A person who is still uncertain about whether they have experienced implantation bleeding or a period can take a pregnancy test to find out if they are pregnant. They should wait a few days after the bleeding has stopped before taking the test, however.

Experiencing heavy bleeding during any stage of pregnancy is a sign of a complication, and a person should seek medical attention.

When to see a doctor

Light bleeding during various stages of pregnancy is typical. It can be caused by a variety of things, such as irritation from a routine exam, sex, or a vaginal infection. This light bleeding does not usually last long, but a person who experiences any bleeding should report it to a doctor just to be safe.

A person who experiences heavier bleeding will require medical attention. A heavy or persistent blood flow that is accompanied by menstrual cramps or blood clots may be a sign of serious complications, such as:

  • a molar pregnancy, where a noncancerous tumor develops in the uterus
  • an ectopic pregnancy, in which egg implants somewhere other than the uterus causing a medical emergency.
  • a miscarriage, which is the early loss of a pregnancy

Will a pregnancy test be positive during implantation bleeding?

Pregnancy tests are based on the level of human chorionic gonadotropin (hCG), which is a hormone that increases after implantation.

Around implantation, hCG levels can still be too low to be detected by a pregnancy, but this can vary from person to person. Once hCG reaches certain levels, typically 1-2 weeks after implantation, a pregnancy test will usually be positive.

What does implantation feel like?

In addition to implantation bleeding in some cases, implantation can cause abdominal cramping, bloating, and changes to a person’s cervical mucus. Other than general early pregnancy symptoms that may begin to appear, a person may also experience an increase in their basal body temperature.

Learn more about implantation signs and symptoms.

What kind of cramps indicates pregnancy?

The cramps that a person may feel after implantation can feel similar to menstrual cramps. For this reason, knowing and recognizing some of the other early pregnancy symptoms other than a missed period can be helpful.

Implantation bleeding can occur as a newly-formed embryo attaches to the uterine wall and breaks down some of the uterine blood vessels. It may not happen in every case, but is a typical symptom of implantation.

It can be hard to tell the difference between implantation bleeding, menstruation, and spotting. Knowing the signs of early pregnancy can help a person tell the difference. If a person thinks they may be pregnant, they can take a pregnancy test.

However, a pregnancy test may not always be accurate so early in a pregnancy. Waiting about a week can help increase the chance that the test result will be accurate. A person can also see a doctor if they think they may be pregnant.