Antepartum hemorrhage - bleeding in the third trimester of pregnancy - is a potentially deadly complication that can happen for many different reasons. Because of the large number of blood vessels supplying the baby from the mother's circulation, blood loss can occur rapidly. Not all bleeding in pregnancy is dangerous, but a healthcare professional should immediately evaluate any significant bleeding.
The leading causes of APH are placenta previa and placental abruption.
Some less common causes include infections, cervical polyps, and bleeding disorders.
APH can cause death. Get emergency care if you bleed enough to soak a pad in an hour.
Regular prenatal care, including ultrasounds, blood pressure monitoring, and preterm labor monitoring, can help prevent complications from placenta previa and placental abruption.
APH – what is it?
APH - or antepartum hemorrhage - is bleeding from the external genitals after 24 weeks of pregnancy. Hemorrhage is defined as the loss of blood by Taber's Medical dictionary. There can be minor hemorrhage, where only a small amount of blood is lost. Usually, though, this term refers to major hemorrhage, meaning a large amount of blood loss.
Main APH causes
There are many potential causes of bleeding in pregnancy. The first thing to determine is if you are experiencing bleeding or spotting.
The cervix has many tiny blood vessels. These can break relatively easily after trauma. Trauma to the cervix could happen from something as simple as intercourse or strenuous exercise. Cervical bleeding is usually spotting - not enough to soak a pad - and generally resolves without problems.
Bleeding is when you must put on a pad or pantiliner. Problems with the placenta - the organ which supplies the baby with nutrients - can cause a lot of bleeding and be very dangerous to both the mother and baby.
Placenta previa and vasa previa
The placenta is a temporary organ that lets oxygen and nutrients move from the mother's blood to the baby's blood. At the beginning of pregnancy, the placenta implants in the wall of the uterus. Usually, it implants at the top or back of the uterus. If it is low when it implants and crosses the cervical opening, this is called placenta previa.
With placenta previa, when the cervix starts to dilate or open, the blood vessels in the placenta going across the opening break, causing massive and rapid blood loss. Placenta previa happens in 2.9 out of 1000 pregnancies in North America and 5.2 per 1000 pregnancies worldwide.
Vasa Previa is when unprotected blood vessels cross the cervical opening. One cause is when the baby's umbilical cord does not go directly from the belly to the center of the placenta and crosses the membranes outside the placenta first--this is called a velamentous cord insertion.
Vasa Previa can also happen if the placenta develops in two parts or lobes. The blood vessels connecting the lobes are also at risk of lying over the cervical opening. Because it is more difficult to see, an ultrasound can miss vasa previa, which makes it especially dangerous.
Though it is rare, the placenta can separate from the wall of the uterus before delivery. When this happens, it opens the blood vessels connecting the mother to the baby and can cause heavy bleeding.
Abruptions can be partial or complete. If only part of the placenta separates, there may not be as much bleeding. Sometimes, part of the placenta separates but is surrounded by other areas still attached. In this case, it is possible for the bleeding to continue invisibly into the uterine wall or for a clot to form.
A placental abruption usually comes with contractions and pain. If you experience bleeding along with a painful, rigid abdomen that does not relax, seek medical attention immediately.
What are some other causes of APH?
APH can also be caused by infections, cervical polyps, and, more rarely, cervical cancers. Systemic diseases like leukemia and bleeding disorders can also cause it. Regular prenatal care can help diagnose these conditions and prevent complications from them.
Is APH an emergency?
Yes. Any significant bleeding in pregnancy is an emergency and needs care as soon as possible.
If you have enough bleeding that you must put on a pad and change that pad before an hour has passed, you need to head to your local emergency department or labor and delivery unit as soon as possible. Do not drive yourself. Call an ambulance if you are having a large amount of bleeding with the following symptoms:
- A fast heartbeat.
- Cool, clammy skin.
- Rapid breathing.
If you are preparing for possible emergencies, it is a good idea to get familiar with the location of the closest hospital and the right place to go once you are there. For example: in some hospitals, the emergency room will have all pregnant patients over 20 weeks of gestation evaluated in labor and delivery. You could save time by going directly to labor and delivery and calling ahead to let them know you are on your way.
Ways to prevent APH
Half of the deaths from APH come from potentially avoidable factors.
You can't control where the placenta implants in a naturally occurring pregnancy. But, if you know the placenta's position ahead of time through an ultrasound, it makes a big difference in preparing for safe delivery.
Experts recommend checking the cervical length to monitor if the cervix is likely to start opening and to deliver the baby by cesarean section in the cases of a complete placenta previa. Timing of the delivery is also essential to consider, balancing a gestation that will allow for the safe and healthy development of the baby but occur before labor can trigger APH.
The American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine recommend delivering the baby between 36 and 37 weeks, six days.
Preeclampsia is a pregnancy complication that can lead to placental abruption. Getting regular prenatal care to monitor for preeclampsia can help. Some studies show that daily aspirin therapy can reduce the risk of getting preeclampsia. Consult your prenatal health care team to discuss this option's risks and benefits.
Another cause of placental abruption is abdominal trauma—this could be due to a fall, motor vehicle accident, or an assault. Seek care immediately if you sustain any trauma to the abdomen while pregnant. The symptoms may not be immediately apparent, so it is crucial to be evaluated by a professional.
Antepartum hemorrhage happens after 24 weeks gestation. If you are experiencing bleeding during early pregnancy, these articles may be helpful:
For more information on problems with the placenta, see: