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What is implantation

Implantation is the attachment of the fertilized egg when the fertilized egg (now called a blastocyst) has completed its travel through the fallopian tube and adheres to the lining of the uterus. Implantation happens about a week after ovulation with a range of 6-12 days after fertilization.

At the time of ovulation, the egg is released from the ovary. Fertilization of the egg by a sperm usually happens within 12-24 hours after ovulation in the distal part of the fallopian tube. The egg/sperm combination is now called a "zygote" and begins traveling down the Fallopian tube towards the uterus. During that time the fertilized egg multiplies into first 2, then 4 and then 8 and more cells. The fertilized eggs which by then is know as the "blastocyst" enters the uterine cavity about 5-6 days after fertilization and adheres to the lining of the uterus within 1-2 days (6-9 days average after ovulation/fertilization) after reaching the uterus.

What is implantation bleeding or spotting

Implantation bleeding is usually defined as a very small amount of bleeding or spotting that occurs because the embryo implants into the lining of the uterus about 6-12 days after conception Implantation spotting or bleeding occurs shortly before the time you would expect to have a menstrual period, and it can confuse some women into believing that they have a menstrual period. However, implantation bleeding tends to be much lighter than menstrual bleeding.

Implantation bleeding usually presents about a week before your menstrual period is due to begin (or 9 days after ovulation). Many women refer to this as spotting or do not even notice the bleeding at all. The closer to the day when the menstrual cycle is supposed to begin that the bleeding is noticed, the less chance of it being implantation bleeding.

It is important to understand that the blood associated with implantation bleeding is usually not going to be fresh blood. It is not like your regular menstrual period or bleeding. The time it takes for these drops to move out of the body ages the blood and it will usually appear dark brown, even black by the time the spotting occurs. However, occasionally the blood associated with implantation bleeding may be fresh blood and thus may appear more red, more like a menstrual period.

When ovulation occurs, the hormone progesterone prepares the uterus for the implantation of a fertilized egg. This happens every month, even if the woman is not trying to conceive, but only if there is ovulation. The thickened uterine lining will shed each month during the menstrual cycle, usually about 12-16 days after ovulation and when pregnancy has not occured. This shedding, often referred to as a period, or menstrual period will last between three and seven days. If a fertilized egg implants in the uterus, implantation bleeding may show up, usually within a couple of days after implantation, but why does implantation bleeding happen?

After the mature egg is released from the ovary, the corpus luteum increases progesterone levels. Progesterone is a hormone that stays elevated throughout pregnancy makingphysical changes to accommodate the growing fetus. The first job of progesterone is to prepare the uterus for implantation. During the three weeks of the month when a woman is not actively ovulating, the uterine lining is thin with a relatively low blood flow. When progesterone levels rise, the uterine lining starts to thicken and blood flow increases.

At the time of ovulation, the mature egg will move through the fallopian tube toward the uterus. At some point, sperm will meet up with the egg; assuming unprotected sex has occurred at the right time. When the sperm and egg meet-up, the sperm burrows through the thick outer coating of the egg and fertilizes the egg. The blastocyst, as the egg is now called, continues to move through the fallopian tube toward the uterus.

Progesterone has increased the blood flow to the uterine lining, so it now appears thick and blood-rich. The egg moves into the uterus and snuggles against one of the thicken walls. When the blastocyst meets the uterine lining, it merges with the uterus; implantation. When this merge happens, a small amount of blood may be released. The cervix has yet to close, so the blood passes through the uterus and out of the vagina. This is implantation bleeding.

Is spotting a sign of pregnancy? Sometimes

Take the Implantation/Spotting Quiz and find out what it could be

Some women don't experience implantation bleeding and others don't notice it. It's also possible to mistake implantation bleeding for a light period. If this happens, you might not realize that you're pregnant — which can lead to mistakes when determining a baby's due date.

Implantation bleeding is light, stops on its own and doesn't require treatment. If you're concerned about any vaginal bleeding or vaginal bleeding during pregnancy, contact your health care provider.

When Does Implantation Bleeding Occur?

Implantation and implantation bleeding occur on average about 9 days after ovulation (range between 6-12 days), which is about a week to a few days before your period would normally start. Implantation bleeding and spotting is among the very first of the typical pregnancy symptoms and pregnancy signs. It is thought to happen when the fertilized egg attached to the lining of the uterus.

Spotting that occurs around a week after ovulation can be implantation bleeding; whereas spotting that occurs much later and a couple days before your period would normally start may not be. A normal menstrual cycle generally starts off light and then gets heavier. 

What you may consider to be implantation spotting can sometimes be the sign of an early period and that means you are not pregnant. If this is the case, the spotting will pick up to heavier bleeding. If you have spotting right around the time your period would normally start, it can be more confusing. You will need to take the wait and see approach or take a pregnancy test to determine pregnancy.
Some women report having around that time implantation symptoms like implantation cramps, implantation bleeding or implantation cramping.

Implantation bleeding usually consists of a couple of drops of blood, which can be either red or brown. If the bleeding is heavier more like a period, then it's unlikely implantation bleeding.

Most pregnant women, however typically have little to no symptoms on the day of implantation and do not experience typical implantation bleeding, while some women who are not pregnant may experience some spotting which they believe could be implantation.

Some women experience bleeding upon implantation while others never do. Having bleeding can also be confused with having menstrual bleeding or your period. This form of bleeding when you are pregnant is normal and requires no specific treatment but you can have a normal pregnancy without it.

Fertilization happens in the fallopian tube, and the fertilized egg then travels for about 5-6 days down the fallopian tube towards the uterus.
Implantation happens when the fertilized egg arrives in the uterus and attaches to the uterine lining. Implantation occurs on average 9 days after ovulation and fertilization, it can happen as early as 6 days after ovulation until 12 days after ovulation

The timing of implantation spotting is within a day or so after implantation, about 9-10 days after ovulation and fertilization. Implantation happens between 6 and 12 days after ovulation, so about 9-10 days after ovulation would be the right time for implantation bleeding and spotting.
A blood pregnancy test can be positive about three to four days after implantation and a urine pregnancy test will be positive about five to six days after implantation.

A study: Timing of implantation

One of the most interesting questions are when does implantation happen exactly? Implantation is when the fertilized egg arrives inside the uterus after having travelled through the Fallopian tube and then attecahes or implants to the lining of the uterus.

Based on a study published in 1999 by Wilcox, implantation happens on average 9.1 days after ovulation and fertilization with a range of 6-12 days.

The egg becomes fertilized with a sperm within 12 hours after ovulation, usually in the outer portion of the fallopian tube. It then travels down the fallopian tube, increasing its size along the way. In the fallopian tube it becomes the zygote and doubles to two cells, four cells, then eight cells and becomes the "morula."

As the morula enters the uterine cavity it's called a "blastocyst." Implantation happens when the fertilized egg (blastocyst) attaches to the uterine wall and starts producing the pregnancy hormone hCG.
In 84% of pregnancies, however, implantation happened between days 8 and 10 after ovulation. There was an increase of miscarriages when implantation happened later. The rate of early pregnancy loss was 13% when implantation happened by day 9, it rose to 26% with implantation on day 10 after ovulation, it rose to 52% if implantation was on day 11 after ovulation, and to 82% if implantation was later than 11 days after ovulation.

Literature: Time of Implantation of the Conceptus and Loss of Pregnancy; Allen J. Wilcox, M.D. et.al. NEJM Volume 340:1796-1799

On Which Day Does Implantation Happen?

The attachement of the embryo to the uterine wall usually happens within 1-2 days after the embryo has arrived in the uterus, about 5-7 days after ovulation and fertilization, on average, 9 days after ovulation and fertilization, with a range between 6 and 12 days.

Is It Implantation Bleeding or a Menstrual Period Bleeding?

Pregnancy related bleeding usually presents about a week before your menstrual cycle is due to begin (or a week after ovulation). Many women refer to this as spotting or do not even notice the bleeding at all.

It is important to understand that the blood associated with implantation bleeding is not going to be fresh blood. The time it takes for these drops to move out of the body ages the blood. It will appear dark brown, even black by the time the spotting occurs.

mittelschmerz ovulation pain cramping


Possible reasons for implantation cramps and cramping

For many women cramps and cramping are a normal part of their menstrual cycle, while for others it may signify implantation cramps and pregnancy.

Uterine cramps or cramping in the lower abdomen can have many possible causes. Mild cramps are often normal, but occasionally cramps can be a sign of bigger problems. When you have cramps, you should first ask yourself: "Am I pregnant?" A negative pregnancy test usually excludes a pregnancy. Uterine cramps are too non-specific to assume that you may be pregnant. Uterine cramps before you miss your period are rarely, if ever, a reliable sign of pregnancy. Typical uterine cramps without being pregnant or before your menstrual period are usually caused by an increase in prostaglandin hormones, chemicals that increase shortly before your menstrual period. In general, among the many causes for cramps are:

To assess the possible cause of cramps, you should be able to answer the following questions:

  1. Do I have a condition explaining the cramps?
  2. Where are the cramps (very low, high, or above the uterus)?
  3. Are the cramps located more in the middle, more on one or the other side, or all over?
  4. Are they mild, moderate, or severe?
  5. Are they rhythmic (for example, every 3-4 minutes or so)
  6. How long do they last (minutes, hours, days)?
  7. Do they happen only on certain days of the menstrual cycle (keep a diary)?
  8. Do they typically go away when the menstrual period begins?

If in doubt, have your doctor examine you to find out what it could be.

Is Implantation Bleeding Common?

Implantation bleeding is fairly common with pregnancy and maybe around twenty to thirty percent of women will have spotting at implantation and during early pregnancy. If you have some light spotting before your period would normally start this is not something to worry about and may be a sign of pregnancy.

Implantation happens about 9 days (range 6-12 days) after ovulation, and you can then have a typical BBT pregnancy chart. Most women report at most a few drops of blood, maybe one to two small red or brown spots in your underwear.Bleeding similar to a menstrual period is unlikely implantation bleeding.

The bleeding or spotting is a result of the egg implanting in the endometrial lining of the uterus. It happens in most pregnancies, but not every woman notices the blood. Between 20 and 30% of women have spotting associated with the early changes of pregnancy but this spotting is not the same as pregnancy bleeding

Does implantation bleeding always happen?

Some women report spotting around the time the egg implants into the uterus. There are few data available on how often this happens. But it's likely that most women who become pregnant do not experience implantation bleeding, and many women who are not pregnant experience some spotting. So when you have spotting 6-12 days after ovulation, this could be implantation spotting or bleeding. But you cannot be sure that you are pregnant until after the pregnancy test is positive, usually about 5-7 days after implantation has happened.in most cases.


Do you feel pain with implantation bleeding spotting?

There is no complete agreement among experts whether it can be felt or not. Some women claim they can feel implantation while many pregnant women did not have any symptoms at that time.

Difference Between Implantation Bleeding and Menstrual Bleeding aka Your Period

There are four characteristics of the bleeding or spotting that can differentiate between a period or implantation symptoms. You can identify whether the bleeding is associated with implantation or a menstrual period by the following characteristics:

  1. TIMING: Implantation bleeding happens about 6-12 days after ovulation while a menstrual period happens 14 days after ovulation
  2. CHARACTER: Implantation bleeding is just a couple of drops while a menstrual period is much more
  3. COLOR: A menstrual period is usually bright red while implantation is more brownish
  4. DURATION:Bleeding associated with implantation lasts up to one day while a menstrual period lasts 3-5 days 

If what the woman feels is implantation bleeding is followed by a lighter flow or normal menstrual cycle, the blood was probably not associated with the implantation of the egg.

When the egg is released from the ovary, it travels down the fallopian tube toward the uterus. If the egg meets up with a viable sperm during the trip and the egg is fertilized, it will attempt to implant in the lining of the uterus. Implantation happens on average about 9 days after ovulation/fertilization and is required for the fetus to continue to grow. If implantation is not successful, the egg will flush out of the body with the normal menstrual flow.

The lining of the uterus is rich in blood and nutrients. When the fertilized egg enters the uterus, the egg "sticks" the this lining, referred to as the endometrial lining. The endometrial lining is the same lining that sheds every month during the menstrual cycle if a fertilized egg does not implant. Implantation occurs between 6 to 12 days after the egg is fertilized.

Due to the blood rich nature of the endometrial lining, a few drops of blood could move through the cervix and down the vagina. This blood is referred to as implantation bleeding and is a common sign of pregnancy. The blood will not appear red, but rather a darker brown or black due to the time it takes to move from the uterus out of the body.

Implantation is the attachment of the fertilized egg (called a blastocyst, a cluster of tiny cells, smaller than the head of a pin) when it has completed its travel through the fallopian tube and attaches to the lining of the uterus.  Ensuring a healthy endometrium (uterus) lining may help to improve the chances of a positive pregnancy. The amino acid L-arginine has been shown to help facilitate these endometrial secretions, learn more about the potential benefits of l-arginine here

Implantation bleeding and spotting is vaginal discharge that usually contains small amount of pinkish or brownish blood. Only about a third of all pregnant women experience this implantation bleeding. Some women report some bleeding or spotting around the time of implantation, the so called "implantation bleeding."

Implantation bleeding, also called implantation spotting, does not look like a regular menstrual period. Implantation bleeding is scanty and usually pink or brownish discharge. Implantation bleeding is often brown in color though some mention it to be more reddish.