What Causes Bleeding During the First Trimester of Pregnancy?

What Causes Bleeding During the First Trimester of Pregnancy?

Last update: 28 September, 2017

Vaginal bleeding is worrying at any stage of pregnancy. It is always considered a reason to consult with a physician. Sometimes it has to do with minor problems, but other times there may be a more serious reason for it.

Many women experience bleeding during the first trimester. Of course, it is an alarming symptom, which is why it’s important to know  whether it’s a cause for concern or not. Here is what it means.

The first thing we must look at is the amount of blood, as well as the color. We also need to watch out for any other possible symptoms that may appear. For example, if on top of bleeding, you may have abdominal pain or other unknown symptoms.

It’s also important to be able to interpret the discomfort you feel, as we have been warned that this happens for a particular cause.

What Causes Bleeding During Pregnancy?

Bleeding during first trimester

Even though bleeding during the first trimester can sometimes be a minor symptom, it is always essential to consult a specialist.

It is highly recommended for a physician to check the status of the pregnancy and monitor its development. Minor or major bleeding can mean different things, such as the following examples.

The Embryo Is Being Implanted

This bleeding can occur between the first four and six weeks of pregnancy. It naturally occurs when the fertilized egg tries to implant itself into the wall of the uterus. Sometimes this implantation scrapes the tissue which causes light bleeding.

In most cases, by the time this happens we don’t know that we are pregnant yet. Because of this, the bleeding may be confused with menstruation. It consists of light bleeding that is a pinkish or brown color. Sometimes it is accompanied by light abdominal pain.

The Pregnancy Is Ectopic

An ectopic pregnancy is what happens when the embryo is implanted outside of the uterus. In this case, there can be a loss of blood accompanied by abdominal pain. Generally, this failed implantation is located in the Fallopian tubes and the pregnancy is almost never successful.

Despite the complexity of the condition, the bleeding is light and the color is pretty dark. However, when this process causes the tubes to rupture, the vaginal blood loss can be major. There may be very intense pain in the lower abdomen, as well as the shoulders and lower back. There can be heavy bleeding, days before the pain starts.

The Emergence of Uterine Hematoma

Woman holding pregnant belly in bed

A uterine hematoma is the accumulation of blood in uterine tissue. It is common during the first weeks of pregnancy, which can cause bleeding when it ruptures. When this happens, the loss of blood is major, but it usually isn’t painful. This type of condition is treated with bed rest.


A miscarriage can cause severe hemorrhaging and abdominal pain. When these symptoms occur, a medical examination is crucial in order to check for opening of the cervix. Once you have been assured that the fetus is okay, they will surely put you on bed rest until the bleeding subsides.

While the ending of a pregnancy is tragic, miscarriage is a very common complication of pregnancy. At least half of conceptions end in miscarriage, to the point where it can even happen without us knowing. There are a variety of causes for this, and sometimes this arises from the combination of several factors.

The Development of a Molar Pregnancy

Although it is not common, molar pregnancy can cause bleeding during the first trimester of pregnancy. Vaginal blood loss may be intermittent and mild, but severe bleeding can also occur. Another symptom is swelling in the abdomen, even though the process takes just a few weeks.

It is caused by an abnormal conception, leading to the swelling and misshaping of the uterus. Molar pregnancies are never carried to term, and so a miscarriage occurs that results in different bleeding. Generally the symptoms of this type of pregnancy do not cause pain.

Other Causes

  • Hormonal changes cause bleeding in the time that corresponds to your menstrual cycle
  • Certain vaginal infections may also cause bleeding, such as candidiasis or sexually transmitted infections
  • Tearing caused by a medical procedure or sex can also cause bleeding. This is due to the increased blood flow to the cervix.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.