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8 Common Causes for Bleeding in the First Trimester

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Learn common causes of bleeding during early pregnancy.

Learn common causes of bleeding during early pregnancy.

Bleeding During Early Pregnancy

Perhaps you've noticed a little blood in your undies, or felt a gush and looked down only to see your bed covered in blood. You are immediately full of fear, and with good reason. Bleeding in pregnancy is most commonly associated with a miscarriage so it is natural to assume the worst.

You shouldn't lose all hope. "In the first trimester, 20 to 40 percent of pregnancies can experience vaginal bleeding," says Dr. Mark Trolice, a reproductive specialist at the IVF Center in Orlando. Most women will have normal pregnancies and deliver healthy babies. This article will cover the potential causes of bleeding in the first trimester.

Miscarriage is only one cause of bleeding during pregnancy.

Miscarriage is only one cause of bleeding during pregnancy.

1st Trimester Miscarriage

Let's get the scariest scenario out of the way first. A miscarriage is the natural death of an embryo. It is classified as occurring before the 20th week. Afterwards, the death of an embryo is medically classified as a stillbirth. A miscarriage is sadly one of the most common complications during early pregnancy. According to Medical News Today, roughly one-quarter of all pregnancies end in a miscarriage. 85% of them occur before the 12th week and can potentially occur before a woman realizes she is pregnant.

What Causes a Miscarriage?

There are a variety of issues that can lead to a potential miscarriage.

  • Poor lifestyle habits such as smoking, drinking alcohol, and use of illegal drugs.
  • The International Journal of Obstetrics and Gynecology reports that women who are underweight are 72% more likely to have a miscarriage within the first trimester. Obesity also carries a high risk as well.
  • Weak muscles in the cervix can open the cervical cavity too early during pregnancy.
  • The placenta may have abnormal development. This could lead to the blood supply being interrupted.
  • Abnormally shaped wombs can cause problems for the development of a fetus.
  • Chromosomal abnormalities can cause issues during development. This is actually the most common reason for a miscarriage in the first trimester.

What Are the Symptoms of Miscarriage?

"While any bleeding is alarming, it is not associated with miscarriage unless heavy bleeding occurs—resulting in approximately a 24 percent risk of loss," says Dr. Trolice. "There is no definitive evidence on the amount of bleeding, color of blood, or associated symptoms that will predict a miscarriage."

According to Dr. Ingrid Rodi, these are some potential symptoms. Keep in mind that there is no proven indicator that a miscarriage has occurred, so be sure to seek medical attention if you exhibit any of these symptoms.

  • Bleeding can be the first sign, though it can be misleading as it can be caused by multiple factors. You should see a doctor if the bleeding is heavy.
  • Pain can be a leading symptom. "Women who experience heavy vaginal bleeding with abdominal cramping are more likely to suffer a pregnancy loss," says Dr. Trolice. It is usually around the abdomen or lower back. It can range from a dull, aching pain to feeling like a period cramp. This symptom can also be misleading as cramping and pain can be common during the first trimester.
  • While not common, a decrease in pregnancy symptoms may be noticeable. This can include no longer feeling morning sickness or breasts no longer feeling tender. This is due to the reduction of pregnancy hormones.

How to Diagnose Miscarriage as the Cause of Bleeding

  • Severe and persistent cramping and/or passing large clots can suggest a miscarriage, but they could be from other causes as well. However, passing tissue, which often looks gray or beige in color, is most likely the baby and is a definite sign that you have miscarried. A pelvic exam can also detect tissue matter passing through.
  • Blood tests can find descending HCG levels, which also indicates an impending miscarriage.
  • An ultrasound may show no heartbeat or no fetus, indicating that the miscarriage is complete. You may also see heart tones that are much slower than normal, and/or that the baby is measuring smaller than it should be. This can imply an impending miscarriage.

Implantation Bleeding

Implantation bleeding is (usually) light spotting or bleeding that occurs between 6 to 12 days after conception. This happens when a fertilized egg begins dividing and forms an embryo, which then implants into the uterine wall. It is often one of the first signs of pregnancy and can occur before a woman realizes she is pregnant. Implantation bleeding is completely normal, harmless, and does not require any medical attention. According to the American Pregnancy Association, roughly one-third of pregnant women will experience this bleeding. It can often be confused with regular menstrual bleeding.

How Long Does Implantation Bleeding Last?

It could potentially last for only a few hours. It should not occur beyond three days. Menstrual bleeding, by comparison, can last for three to seven days.

What Are the Symptoms of Implantation Bleeding?

  • Implantation bleeding is reported as usually being pinkish or darker in color than typical menstrual bleeding. However, most women don't find the two types of bleeding to be substantially different.
  • Some women report having clotting during menstruation. Implantation bleeding should not feature any clotting.
  • Implantation bleeding is usually just some spotting or a light flow. It shouldn't be a full flow like a period.
  • It usually comes along with other various early pregnancy symptoms such as light cramping, nausea, and breast tenderness.

How Is Implantation Bleeding Diagnosed?

It can only be verified with a positive pregnancy test or a blood test to read rising HCG levels. It is merely a part of pregnancy and is not a cause for concern.

Ectopic Pregnancy

"This is the implantation of an embryo outside the uterine cavity, most commonly in the fallopian tube," says Dr. Trolice. Less common areas include the cervix, ovary, and abdomen. As an embryo can not develop outside the uterus, this means the embryo is not viable. According to WebMD, this condition must be treated as it can cause a fallopian tube to burst. While an ectopic pregnancy can cause issues for future pregnancies, it does not rule them out. You can have a successful pregnancy after an ectopic pregnancy.

What Are the Symptoms of an Ectopic Pregnancy?

Most women will be unable to recognize an ectopic pregnancy since they will experience most of the regular pregnancy symptoms initially. Vaginal bleeding is a major sign, particularly if it is heavier and lighter in color than normal menstruation. Pain in the abdomen and pelvis is another clue. This is due to blood gathering up under the diaphragm.

How to Treat an Ectopic Pregnancy

"An ectopic pregnancy is a potentially life-threatening situation," says Dr. Trolice. "As long as the patient is stable, the first line of treatment is a methotrexate injection, a chemotherapy used to disrupt the pregnancy cells for the body to absorb. If the patient is medically unstable or has been unsuccessful with conservative treatment, surgery is performed to remove the ectopic pregnancy. This may involve removing the affected fallopian tube."


Cervicitis is the inflammation of the cervix. It can be caused by a number of infections, most commonly by sexually transmitted diseases such as chlamydia and gonorrhea. The cervix can become irritated and potentially lead to some spotting or bloody discharge.

What Are the Symptoms of Cervicitis?

According to Harvard Health, cervicitis usually doesn't have any major symptoms. While not common, some signs do exist such as bloody vaginal discharge or spotting. Here are some potential symptoms of cervicitis.

  • Pain during intercourse.
  • Vaginal itching.
  • Burning feeling when you urinate.

You should consult a doctor if you exhibit any of these symptoms. Cervicitis can spread to your fallopian tubes and ovaries if left untreated.

Cervical Polyps

Cervical polyps are benign growths that appear around the opening of the cervix. According to Healthline, they may appear during pregnancy due to the rise of hormone levels. However, their exact cause remains unknown. While not usually cancerous, they should be examined since rare types of cancers can look like polyps.

What Are the Symptoms of Cervical Polyps?

Cervical polyps typically don't cause any major noticeable symptoms. The biggest sign is usually some light bleeding. It is typically nothing more than spotting, but it can appear as heavier bleeding as well. Bleeding most commonly occurs after intercourse. A doctor can identify polyps during a vaginal exam. If surgery is needed to remove the polyps, you can expect vaginal bleeding for the next day or two. Some women experience a watery discharge with some blood as well.

Subchorionic Hemorrhage

A subchorionic hemorrhage, or subchorionic hematoma or bleed, is when blood accumulates within the chorion or between the placenta and uterus. According to WhattoExpect, about one percent of all pregnancies will experience a subchorionic hemorrhage. It seems to be more prevalent with women who become pregnant via IVF. For women that experience bleeding in their first trimester, a subchorionic hemorrhage is diagnosed as the reason 20 percent of the time. This bleeding is not necessarily dangerous to a mother or her baby but it should be monitored to ensure that no complications arise. Most cases will resolve on their own and women will go on to have healthy pregnancies.

What Are the Symptoms of a Subchorionic Hemorrhage?

This condition is difficult to detect since it usually doesn't have any noticeable symptoms. The only visible signal is some potential light spotting or bleeding.

How to Diagnose a Subchorionic Hemorrhage

This condition is diagnosed most of the time through a routine ultrasound, especially if there was no visible bleeding.

The empty sac on the right side indicates a twin that didn't make it past the embryonic stage. See the blood in the lower half of the sac.

The empty sac on the right side indicates a twin that didn't make it past the embryonic stage. See the blood in the lower half of the sac.

Vanishing Twin Syndrome

This is a phenomena where multiple eggs are fertilized (usually two) but one of the embryos fails to progress. Often, the deceased embryo gets absorbed by the placenta, the mother, or the other baby. This can be considered a type of miscarriage. According to the American Pregnancy Association, if this occurs in the first trimester, there is usually not any risk to the mother or surviving twin. With the development of ultrasonography, experts now believe VTS occurs in roughly 21-30 percent of all multiple pregnancies.

What Causes Vanishing Twin Syndrome?

The exact cause is unknown. Examination of fetal tissue or placenta has often revealed some type of chromosomal abnormality. Improper cord implantation can also be a key factor as well. According to Dr. Robert Wool, VTS is more likely with fraternal twins since that type of twin is a sort of genetic malfunction to begin with.

How is Vanishing Twin Syndrome Diagnosed?

An ultrasound is the only way to diagnose VTS during the 1st trimester. A follow-up ultrasound will notice the disappearance of the second fetus that was previously visible. A Doppler may also only read one heartbeat where two were previously detected.

Decidual Bleeding

Decidual bleeding is a condition related to the partial shedding of the lining of the uterus during the first trimester. This shedding is believed to be caused by hormonal imbalances. According to Prime Health Channel, it is caused by portions of the decidua that has yet to be covered by the embryo or placenta. The passage of this tissue may be confused with a miscarriage or menstrual blood.

What Are the Symptoms of Decidual Bleeding?

This type of bleeding usually appears as spotting or bleeding that can be comparable to menstrual-like bleeding. As such, it is often confused for a period. Blood clots may be passed, and there may be small pieces of uterine lining present. This can cause some confusion as women may mistake this as a symptom of a miscarriage.

How to Diagnose Decidual Bleeding

As with all bleeding, a doctor should be consulted as it may be a sign of a major problem. An examination can find decimal bleeding to be a cause if no major complications are present.

When Is 1st Trimester Bleeding a Medical Emergency?

According to the Mayo Clinic, you should seek a doctor if you have any type of bleeding that has lasted over a day. You should seek immediate medical attention if you experience any of the following.

  • Moderate to heavy vaginal bleeding.
  • Passing tissue from your vagina.
  • Any vaginal bleeding that is accompanied by fever, cramping, or abdominal pain.
  • Feeling any dizziness or experience fainting.

What Is Rh Incompatibility in Pregnancy?

An important reason to see a doctor for any type of bleeding is the condition known as Rh incompatibility or Rh isoimmunization. "If a pregnant woman bleeds and her blood type is Rh negative, and the sperm source is Rh positive or unknown, then the woman has the potential of developing antibodies that can harm the baby who is Rh positive," says Dr. Trolice. "This can result in severe anemia, jaundice, brain damage, and heart failure in a newborn."

According to the National Heart, Lung, and Blood Institute, Rh incompatibility can be treated with injections of Rh immune globulin. This medicine prevents your body from creating Rh antibodies that will harm your baby.

What to Do If You Experience 1st Trimester Bleeding

If you become one the of 20% of women who experience 1st trimester bleeding, stay calm and remember that no matter how heavily you are bleeding, there are several possible explanations besides miscarriage.

Let your doctor or midwife know what you are experiencing. Your doctor may tell you to go to the emergency room or labor and delivery to be checked out. Understand that a 1st trimester miscarriage in progress cannot be stopped. The main benefit to going in right away is that you will hopefully find out immediately what is going on.

Know, however, that you do have the option of staying at home until normal office hours, or to miscarry naturally in an environment in which you will be more comfortable. According to the American Pregnancy Association, a D&C procedure is not usually necessary unless the miscarriage occurred later than 10-12 weeks or if there are any related complications.

Overall, it is suggested to call a doctor for any type of noticeable bleeding that you feel is unusual. Here are some other steps you can take.

  • Wear pads so you can monitor how much you are bleeding as well as what type of bleeding you are experiencing.
  • Do not use a tampon or introduce anything into the vaginal area if you are bleeding. Avoid sexual intercourse as well.
  • Contact a doctor if you experience cramps or abdominal pain.
  • If you happened to have collected any tissue you passed through, you could bring that to a doctor for examination.