Bleeding when pregnant sounds scary, and it certainly can be. However, about 20% of women experience some bleeding during their first trimester of pregnancy. Some causes of bleeding during pregnancy are normal and not necessarily a sign that something is wrong, but you should be aware of what bleeding when pregnant means and when you should see your doctor.
Benign Causes of Bleeding When Pregnant
Within the first six to twelve days post-conception, you may experience some spotting as the fertilized egg implants in the lining of the uterus. This is often mistaken as a period by women who don’t yet realize they are pregnant. This type of bleeding when pregnant is usually very light, lasting from a few hours to a few days.
Pregnancy causes extra blood to flow to the cervix. As a result, intercourse or pelvic exams can cause light bleeding. This is normal and no cause for concern.
A harmless growth on the cervix, cervical polyps are more likely to bleed during pregnancy as a result of increased estrogen levels and the increased number of blood vessels in the tissue around the cervix.
Abnormal Causes of Bleeding During the First Half of Pregnancy
Unfortunately, 15% to 20% of pregnancies end in miscarriage within the first twelve weeks of pregnancy. While we don’t always know why a pregnancy has ended in misacarriage, the majority of early losses are related to chromosomal issues limited to that specific pregnancy, and are not related to maternal factors. If you are experiencing continued bleeding, or cramping combined with bleeding, you should reach out to your care team.
Also known as a subchorionic hemorrhage, this particular condition develops when the placenta partially detaches from the uterine lining. This can cause bleeding between the uterine lining and the outer fetal membrane (called the chorion). A subchorionic hematoma is a relatively common cause of first trimester bleeding, and it usually resolves on its own. However, because it can sometimes result in an elevated risk of pre-term labor or miscarriage, most OBGYNs will want to closely monitor this condition.
An ectopic pregnancy occurs when the egg implants itself somewhere outside the uterus, most often in the fallopian tubes. Ectopic pregnancies happen in 1 out of 50 pregnancies. Along with bleeding, you may experience strong abdominal cramping low in the stomach, sharp pain in the abdominal area, and low HCG levels.
A rare cause of early bleeding, molar pregnancies involve the growth of abnormal tissue instead of the embryo. Along with bleeding, tests may reveal high HCG levels, absent fetal heart tones, and grape-like clusters seen in the uterus by ultrasound.
Some vaginal and uterine infections can also cause bleeding. When assessing vaginal bleeding in pregnancy, your midwife or doctor will often screen for common infections.
Abnormal Causes of Bleeding During the Second Half of Pregnancy
This case is extremely rare, occurring in only 1% of pregnant women, and more likely during their last twelve weeks of pregnancy. Placental abruption occurs when the placenta detaches from the uterine wall before or during labor. Along with bleeding, you may have stomach pain.
You are at a higher risk for placental abruption if you:
- Have already had children
- Are over 35
- Have a history of abruption
- Have hypertension
- Have sickle cell anemia
- Have had trauma or injury to your stomach
- Use cocaine
This very serious condition occurs when the placenta lies low in the uterus either partly or completely covering the cervix. It requires immediate medical attention. Occurring in 1 out of 200 pregnancies, the bleeding is not usually accompanied by pain.
You are at a higher risk for placenta previa if you:
- Have already had children
- Had a previous cesarean birth
- Had other surgery on the uterus
- Are carrying twins or triplets
The mucus plug sometimes passes up to a few weeks before labor begins, it is made up of mucus and blood. If it occurs any earlier, you may be entering preterm labor. Other signs include:
- Watery mucus or bloody discharge
- Pelvic or lower abdominal pressure
- Low, dull ache in back
- Stomach cramps
Rare Causes of Bleeding During Pregnancy
There are some rare conditions which can cause vaginal bleeding. The vast majority of vaginal bleeding is benign, but the following conditions can be quite serious even if they are also incredibly uncommon. Talk to your OBGYN or care team immediately if you are worried your bleeding is caused by either of the following.
A uterine rupture occurs when the scar from a previous Cesarean-section surgery tears during your pregnancy. Again, the chances of such an occurrence are relatively remote, but it does happen. Symptoms of a uterine rupture can include:
- Significant vaginal bleeding.
- Sudden, noticeable pain around the site of your previous C-section incision.
- Soreness and pain of the abdomen.
- A bulge under the pubic bone or the movement of the baby’s head into the birth canal.
In some cases, uterine ruptures may occur during delivery, in which case your contractions could change or slow.
The treatment for uterine ruptures will usually involve an emergency c-section.
Vasa previa is also incredibly rare. When it occurs (and when it is detected), symptoms usually present shortly before labor starts.
Typically, the blood vessels in the umbilical cord and placenta are contained by a membrane. Vasa previa occurs when that membrane is ruptured and blood begins to cross the opening to the birth canal. Left untreated, this can cause the baby to lose blood and suffer from oxygen deprivation.
Symptoms of vasa previa include:
- Significant and painless vaginal bleeding.
- Unsteady fetal heartbeat or fluctuating vital signs.
- Detected rupture of membranes (although this symptom may not be observable to patients).
Vasa previa is often treated by closely monitoring your baby’s health. The idea is to give your baby as much time to develop safely as possible before inducing labor. In some cases, complete bed rest is recommended. Your OBGYN may also admit you to a hospital during your third trimester for close observation and treatment.
Both vasa previa and uterine ruptures are quite rare, but if you suspect you may be experiencing symptoms, it’s important to see your physician or OBGYN immediately. In most cases, prompt intervention can lead to a healthy outcome for both you and your baby.
What Should You Do If You’re Bleeding When Pregnant?
While there is often no cause for alarm, bleeding when pregnant can be a sign that something is wrong, so you should always consult with your midwife or doctor. They will be able to determine whether your bleeding is normal or cause for concern.
It’s a good idea to use pads or a panty liner to keep track of the amount of blood flow to report to your care team. You should avoid the use of tampons.
Together, you and your healthcare provider can discuss and take the appropriate next steps for the health and safety of yourself and your baby.
If you have questions or would like more information, please call our Wilmette or Glenview offices. If you have other pregnancy related questions, please feel free to look through our obstetrics blog library. We add to it regularly.