Postpartum hemorrhage is excessive bleeding after childbirth, defined as losing more than 1,000 mL of blood within 24 hours of delivery. It is the leading cause of maternal death worldwide, accounting for more than 20% of all maternal deaths and affecting millions of women every year.
How It’s Defined
The American College of Obstetrics and Gynecology updated its definition in 2017 to a single threshold: cumulative blood loss of more than 1,000 mL combined with signs of significant blood loss (dizziness, rapid heart rate, low blood pressure) within 24 hours of birth, regardless of whether delivery was vaginal or cesarean. That said, losing more than 500 mL during a vaginal delivery is still considered abnormal and may require intervention. Blood loss during delivery is routinely underestimated by medical teams, which is one reason the definition was broadened.
For context, 1,000 mL is roughly a quart of blood. The average adult has about 5 liters total, and pregnant women carry extra blood volume to support the baby, but losing a liter quickly still puts serious strain on the body.
Primary vs. Secondary Hemorrhage
Primary postpartum hemorrhage happens within the first 24 hours after birth. This is the more common and more dangerous type, often occurring in the delivery room or recovery area while the medical team is still present.
Secondary postpartum hemorrhage is significant vaginal bleeding that starts anywhere from 24 hours to six weeks after delivery. It’s less common but can catch new parents off guard because it happens after they’ve gone home. The most frequent cause is endometritis, an infection of the uterine lining, which accounts for roughly 67% of secondary cases. Retained placental tissue, where small fragments of the placenta remain inside the uterus, is the second most common cause at about 21%. Women who delivered by cesarean section have higher rates of infection-related secondary hemorrhage, while those who delivered vaginally are more likely to have retained tissue as the cause.
The Four Main Causes
Doctors organize the causes of primary postpartum hemorrhage into four categories, sometimes called the “four Ts”: tone, tissue, trauma, and thrombin. Understanding these helps make sense of what’s happening and why treatment takes the form it does.
Tone refers to the uterus not contracting properly after delivery. This is called uterine atony, and it’s by far the most common cause. After the placenta detaches, the uterus needs to clamp down on the blood vessels at the former placenta site. When those muscles don’t tighten, the vessels keep bleeding freely. Factors that stretch the uterus beyond normal, like carrying multiples, having a very large baby, or excess amniotic fluid, increase this risk. A long or very fast labor can also exhaust the uterine muscle.
Tissue means part of the placenta or membranes stayed behind. Even a small fragment can prevent the uterus from contracting fully, keeping blood vessels open.
Trauma covers tears to the cervix, vagina, or perineum during delivery, or more rarely, uterine rupture. Assisted deliveries using forceps or vacuum increase the chance of these injuries.
Thrombin refers to blood clotting problems. Some women have pre-existing clotting disorders, while others develop clotting issues during pregnancy or delivery (for example, from severe preeclampsia or a placental abruption). When blood can’t clot normally, even small tears or the normal placental wound site can bleed excessively.
Who Is at Higher Risk
Some risk factors are identifiable before or during labor. A previous postpartum hemorrhage is one of the strongest predictors. Other factors include:
- Overdistended uterus: from twins, triplets, a large baby, or excess amniotic fluid
- Prolonged labor: especially if labor-stimulating medications were used for an extended period
- Multiple previous deliveries: the uterine muscle becomes less efficient at contracting with each pregnancy
- Placental abnormalities: conditions where the placenta attaches too deeply into the uterine wall or covers the cervix
- Cesarean delivery: involves more surgical surfaces that can bleed
- Obesity and advanced maternal age: both independently raise the risk
That said, postpartum hemorrhage can happen to anyone. Roughly 40% of cases occur in women with no identifiable risk factors, which is why hospitals prepare for it at every birth.
What It Looks and Feels Like
Some bleeding after delivery is normal. The body sheds the uterine lining over the following weeks in a process called lochia. Postpartum hemorrhage is different in volume and speed. In primary hemorrhage, you or the medical team will notice heavy, continuous bleeding that soaks through pads rapidly, sometimes with large clots.
The body’s response to significant blood loss includes a racing heart, feeling lightheaded or faint, pale or clammy skin, and confusion. One clinical tool that helps catch hemorrhage early is the shock index: your heart rate divided by your systolic blood pressure. A value above 0.9 signals that intervention is needed, even if individual vital signs still look borderline normal. Medical teams monitor this because the body can initially compensate for blood loss, masking how serious the situation is until it becomes critical.
For secondary hemorrhage, the warning sign is a sudden return of heavy bleeding days or weeks after delivery, sometimes accompanied by fever, foul-smelling discharge, or pelvic pain, which point toward infection.
How It’s Prevented
The single most effective prevention strategy is active management of the third stage of labor, the period between the baby’s birth and delivery of the placenta. This involves giving a preventive dose of a uterus-contracting medication immediately after the baby is born, then using gentle, controlled traction on the umbilical cord to help deliver the placenta. This approach significantly reduces the risk of hemorrhage compared to a hands-off, wait-and-see approach.
How It’s Treated
Treatment escalates in stages depending on severity and the underlying cause. The first step is almost always uterine massage, where a provider firmly kneads the uterus through the abdomen to stimulate contraction. This is uncomfortable but often effective for atony-related bleeding.
If massage alone isn’t enough, medications that cause the uterus to contract are given. The first choice works the same way as the hormone your body naturally releases during labor. If that doesn’t control the bleeding, stronger alternatives are available, each targeting the uterine muscle through different pathways. Some are given as injections, others rectally for rapid absorption. The medical team chooses based on what’s working and any conditions you might have (certain options aren’t safe for women with high blood pressure or asthma, for example).
When medications fail, the next step is mechanical. A balloon device can be inserted into the uterus and inflated with about 500 mL of saline, applying direct pressure against the bleeding vessels from the inside. The most commonly used version is the Bakri balloon. It stays in place for 12 to 24 hours and is then deflated and removed. Research shows that inserting the balloon earlier rather than later is associated with significantly less total blood loss.
If the balloon doesn’t work, surgical options include procedures that compress the uterus with sutures or block blood flow to the uterine arteries. A hysterectomy, removing the uterus entirely, is the last resort and is only performed when all other options have failed and the bleeding is life-threatening. Blood transfusions may be needed at any stage to replace what’s been lost.
The Global Picture
More than 80% of maternal deaths from postpartum hemorrhage occur in sub-Saharan Africa and South Asia, where access to skilled birth attendants, medications, and blood transfusions is limited. In high-resource settings, deaths from postpartum hemorrhage are far less common but still occur, often because of delays in recognizing the severity of bleeding. The gap between these outcomes underscores that postpartum hemorrhage is largely treatable when caught early and managed with the right resources.