Implantation Bleeding: Signs, Causes, What To Expect

If you are trying to get pregnant, you may be paying attention to every possible sign that your baby is on the way. 

One of the earliest pregnancy signs you should be aware of is implantation bleeding. 

Recognizing this sign can give you an idea that you are as early as two weeks pregnant.

In this article, we tell you everything you need to know about implantation bleeding, including what it means, when it happens, why it happens, how to recognize it, and how to differentiate it from other types of vaginal bleeding. 

What is implantation bleeding?

Implantation bleeding refers to the light bleeding that is seen when a fertilized egg attaches (implants) itself to the inner lining of your uterus.

During ovulation, which usually occurs between days 11 and 14 of the menstrual cycle, an egg is released from the ovaries. 

The egg moves into the fallopian tube with the help of tiny finger-like projections known as fimbriae. 

While the egg moves down the fallopian tubes towards the uterus, it can get fertilized by sperm if unprotected sexual intercourse occurs.

The fertilized egg (known as a zygote) then travels down through the fallopian tube and into the uterus while it undergoes multiple cell divisions. It first divides into 2 cells, then splits into four cells, and so on. 

By one week, the zygote becomes a cluster of many cells. This group of cells is known as a blastocyst.

Implantation occurs after these series of events have taken place. When the cluster of cells reaches the uterus, it embeds itself into the uterine wall, where it gets blood supply and nutrition to grow into a fetus. 

During this process of embedding itself, the blastocyst may affect some of the blood vessels in the uterus, leading to what is known as implantation bleeding.

This is a normal sign of pregnancy. It does not pose any problems to the mother or the developing baby and does not need any treatment.

Implantation bleeding typically occurs between 10-14 days after conception. This can cause some confusion because it is usually around the time you expect your period. 

As a result, women may mistake this bleeding for menstrual flow. However, some features can help you differentiate between the two. We will discuss them discuss later.

Is implantation bleeding common in early pregnancy?

Only about a third of expecting mothers have implantation bleeding. So, while it is relatively common, not all women will experience it.

Also, if you have been pregnant before and you had implantation bleeding, it does not mean that you will have the same sign during your subsequent pregnancies.

When does implantation bleeding occur?

Implantation bleeding occurs when the embryo embeds into the uterine wall, usually during the first two weeks after conception. 

The exact time varies between women, but it is said to occur about 6 to 12 days after fertilization. 

Most women are unaware that they are pregnant during this time and do not even notice implantation bleeding.

Signs and symptoms of implantation bleeding

Implantation bleeding is one of the earliest signs of pregnancy. The bleeding is usually light and may appear as a spot/streak of blood on your underwear or toilet paper. 

There may be other accompanying early pregnancy symptoms such as:

• Tiredness
• Headache
• Nausea
• Pain in the breast (breast tenderness)
• Bloating
• Mood swings

What does implantation bleeding look like?

The main thing that differentiates implantation bleeding from other types is that it is light bleeding. 

It may be light pink, brown, or dark brown blood that is not enough to soak a pad. 

If you have vaginal bleeding that is heavy enough to soak a pad, it is likely not implantation bleeding.

How to recognize implantation bleeding

One of the most important things to pay attention to is the timing. It usually occurs within two weeks of conception. 

So, if you are trying to get pregnant and are experiencing some light bleeding within two weeks of your last ovulation, it may be an implantation bleed. 

But you also need to pay attention to how the blood looks and the pattern of the bleeding. 

Here are a few characteristics to look out for:

• Spotting or light bleeding, which is not enough to soak a pad or tampon
• Does not contain any clots
• Slightly pink in color. It could be brown or dark brown as well.
• Does not last for more than three days
• Mild or no cramping (not as intense as period cramps)

It is likely not be implantation bleeding if:

• It is heavy (especially if it soaks more than one pad a day)
• Contains blood clots
• Bright red in color
• Occurs with serious cramping

If you experience the above symptoms, it could be due to some other cause of vaginal bleeding. We talk about those in more detail later. 

Contact your healthcare provider if you experience heavy vaginal bleeding, cramping, or clotting, as it may be a sign of a serious underlying problem.

How long does implantation bleeding last?

How long implantation bleeding lasts varies from woman to woman.  It can last only a few hours for some and a few days for others. It is not usual for this bleeding to go beyond three days, however.

How heavy is implantation bleeding?

This type of bleeding is light, with only enough spots to stain your underwear or pad.

It is believed that women who are pregnant for the first time are likely to bleed more than those who have been pregnant before because their wombs have never had an egg implant in them.

Why does implantation bleeding happen?

After fertilization, the fertilized egg starts to move down the fallopian tube to get to the womb. Around 6-12 days after fertilization, the fertilized egg reaches the womb and embeds itself in the wall of the uterus.

The inner lining of the wall of the uterus contains blood vessels. During the process of implantation, some blood vessels in the uterine wall may get ruptured, leading to implantation bleeding.

Can you test positive during implantation bleeding?

Pregnancy test kits check for the presence of a hormone called human chorionic gonadotrophin (HCG) in your blood or urine. 

The urine test is more widely available but less sensitive. If you are using a urine pregnancy test kit, it is highly unlikely to test positive during implantation bleeding. 

Here’s why:

After implantation into the uterus, the embryo continues to develop, and the placenta begins to form. This is when HCG starts being produced. 

HCG is produced by special cells in the placenta and is responsible for keeping the lining of the uterus thick in order to help the embryo stay in place. 

Because it comes from the placenta, HCG is not produced until after implantation and placenta formation have occurred.

The hormone can be found in blood and urine. The level of HCG in the blood and urine rises rapidly in early pregnancy, doubling every 48 to 72 hours. 

If you do a urine pregnancy test during implantation bleeding, you may get a false negative result. 

This is because the levels of HCG may be too low to be detected in your urine at that time. 

It is best to wait until 4 to 5 days after your implantation bleeding has stopped to conduct the pregnancy test.

The blood test for HCG detects the hormone much earlier than the urine test can. HCG can be detected in the blood as early as 11 days after conception. 

So, a blood test is more likely to give a positive result during the period of implantation bleeding. You can speak to your doctor about a blood HCG test.

Implantation bleeding vs menstrual period

Because of the timing, it can be difficult to differentiate between implantation bleeding and menstrual flow. 

So, how can you tell whether your bleeding is a sign that you are pregnant or whether your period came early and you should try again in the coming month?

The features of bleeding from implantation and menstruation may vary from woman to woman. But, there are some common features to be aware of.

Color

The color of the blood is a significant clue to guide you. Implantation bleeding is usually slightly pink or brown in color. In contrast, menstrual blood can be bright red, dark red, or brown.

Clots

If you notice any clots present in the blood, it is certainly not implantation bleeding because it does not result in the release of enough blood to form clots. If there are clots, it is likely to be your period.

Duration

If the bleeding lasts for more than three days, you can be certain that it is not implantation bleeding. 

Implantation bleeding does not last beyond 3 days. It can last a few hours and comes as intermittent spotting.

Menstrual periods, on the other hand, can last for up to 7 days. The duration differs from woman to woman. However, the normal duration of days for your period is 2-7 days. 

If you bleed for more than 7 days, consult your health care provider to exclude any abnormality.

Accompanying symptoms

Many women have abdominal cramping during their periods. Implantation can cause cramping, but it is milder and does not last as long. The pain associated with menstrual periods is more intense and can cause more discomfort.

Implantation bleeding may also come with signs of pregnancy, such as headache, nausea, and mood swings. Menstrual bleeding may present with similar symptoms. 

The catch is every woman is different and experiences periods differently. Some may have one, two, or all of these symptoms, while others never experience any of them. 

If you are bleeding lightly and experiencing these symptoms (and you never get them during your period), it may be implantation bleeding.

Flow

Menstrual bleeding is heavier than implantation bleeding. Most women lose between 20 to 90 ml of blood every month. 

The bleeding usually starts as light bleeding and then progressively becomes heavier. But in implantation bleeding, the blood is in spots that are on and off.

Here’s a quick summary showing the differences between menstrual and implantation bleeding:

Characteristics	Implantation bleeding	Menstrual bleeding
Color	Light (slightly pink), brown	Bright to dark red, brown
Presence of clots	No clots	Varying degrees of blood clots can be seen
Duration	Varies between a few hours to three days	Varies between 2-7 days
Presence of accompanying symptoms	No pain or only mild cramping	May be accompanied by more severe abdominal cramps
Flow	Bleeding tends to be light spotting that comes and goes	Menstrual bleeding tends to start light and progressively becomes heavier bleeding

Other causes of vaginal bleeding during pregnancy

Vaginal bleeding is common among pregnant women. While some causes of vaginal bleeding are harmless, others can be dangerous. 

Here is a list of possible causes of vaginal bleeding in early pregnancy:

Miscarriage

This refers to the loss of pregnancy before 20 weeks. Most miscarriages occur in the first trimester at a rate of 15-20%. 

Miscarriages can cause vaginal bleeding, which can vary from light spotting to heavy bleeding with clots and tissue. 

Other possible symptoms include severe lower abdominal pain and weakness.

Ectopic pregnancy

An ectopic pregnancy is a life-threatening condition that occurs when a fertilized egg implants outside the uterus. It is relatively rare and occurs in 1-2% of pregnancies.  

Most ectopic pregnancies occur in the fallopian tubes. Because the tube is too small, it can rupture as the embryo grows bigger. 

This often happens between weeks 6 and 16 and can lead to vaginal bleeding. 

Other symptoms include pain on one side of your lower abdomen, shoulder pain, lightheadedness, and fainting. 

If you are experiencing such symptoms, seek medical attention immediately.

Molar pregnancy

This condition is also known as gestational trophoblastic disease. It occurs when the fertilized egg develops into a mass of abnormal cells or sacs filled with water instead of a fetus. 

These tissues grow rapidly and can lead to vaginal bleeding, usually between 6-12 weeks. 

Other symptoms include extreme nausea and vomiting and passage of cysts that resemble grapes from your vagina.

Subchorionic hematoma

This refers to bleeding beneath the chorion, one of the membranes that enclose the embryo in your uterus. It is believed to occur when some part of the chorion detaches from the uterine wall. 

Vaginal bleeding is the most common symptom, and it usually occurs between 10-20 weeks. 

Some women have accompanying abdominal pain. Others have no symptoms at all. 

Subchorionic hematomas usually heal on their own without any intervention.

Infections

Infections in the vagina or cervix – especially sexually transmitted infections (STIs) like Chlamydia, gonorrhea, trichomoniasis, and herpes – can cause inflammation and lead to vaginal bleeding during pregnancy. 

Other possible symptoms include itching, a burning sensation when urinating, and foul-smelling vaginal discharge.

Irritation during intercourse

Lack of lubrication during penetrative sex can lead to irritation and tears, which may result in bleeding. 

Also, because of hormonal changes, the cervix becomes extra sensitive during pregnancy which can lead to bleeding during or after sex.

Cervical polyps

Cervical polyps are finger-like noncancerous growths that originate from the cervix. If you have a cervical polyp, hormonal changes (increased estrogen levels) in pregnancy can make it more sensitive and lead to vaginal bleeding.

Conclusion

Implantation bleeding is one of the earliest signs of pregnancy. It occurs when the embryo embeds itself into your uterine wall and disrupts blood vessels there. 

Only about a third of pregnant women experience implantation bleeding. Because of the time it occurs, it is commonly mistaken for menstrual bleeding. 

However, there are some differences in its characteristics. It is usually light bleeding that only spots your underwear or pad. The bleeding does not contain any clots and does not soak the pad or tampon. It typically lasts for a few hours and does not go beyond 3 days.

If you think you have had an implantation bleed, you may be excited and want to confirm with a pregnancy test immediately. 

However, it is recommended to wait a few days after implantation bleeding has occurred before you do a urine pregnancy test because there could be a false negative if done too early.

Implantation bleeding is a harmless cause of bleeding during early pregnancy. Other possible causes are a miscarriage, ectopic pregnancy, and molar pregnancy. 

If you think you are pregnant and have heavy bleeding and/or abdominal pain, contact a healthcare provider as soon as possible.

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