Postpartum bleeding or postpartum hemorrhage (PPH) is often defined as the loss of more than 500 ml or 1,000 ml of blood within the first 24 hours following childbirth. Some have added the requirement that there also be signs or symptoms of low blood volume for the condition to exist. Signs and symptoms may initially include: an increased heart rate, feeling faint upon standing, and an increased breath rate. As more blood is lost, the woman may feel cold, blood pressure may drop, and she may become restless or unconscious. The condition can occur up to six weeks following delivery. Postpartum bleeding or postpartum hemorrhage (PPH) is often defined as the loss of more than 500 ml or 1,000 ml of blood within the first 24 hours following childbirth. Some have added the requirement that there also be signs or symptoms of low blood volume for the condition to exist. Signs and symptoms may initially include: an increased heart rate, feeling faint upon standing, and an increased breath rate. As more blood is lost, the woman may feel cold, blood pressure may drop, and she may become restless or unconscious. The condition can occur up to six weeks following delivery. The most common cause is poor contraction of the uterus following childbirth. Not all of the placenta being delivered, a tear of the uterus, or poor blood clotting are other possible causes. It occurs more commonly in those who: already have a low amount of red blood, are Asian, with bigger or more than one baby, are obese or are older than 40 years of age. It also occurs more commonly following caesarean sections, those in whom medications are used to start labor, those requiring the use of a vacuum or forceps, and those who have an episiotomy. Prevention involves decreasing known risk factors including procedures associated with the condition, if possible, and giving the medication oxytocin to stimulate the uterus to contract shortly after the baby is born. Misoprostol may be used instead of oxytocin in resource poor settings. Treatments may include: intravenous fluids, blood transfusions, and the medication ergotamine to cause further uterine contraction. Efforts to compress the uterus using the hands may be effective if other treatments do not work. The aorta may also be compressed by pressing on the abdomen. The World Health Organization has recommended non-pneumatic anti-shock garment to help until other measures such as surgery can be carried out. A 2017 study found that tranexamic acid decreased a woman's risk of death. In the developing world about 1.2% of deliveries are associated with PPH and when PPH occurred about 3% of women died. Globally it occurs about 8.7 million times and results in 44,000 to 86,000 deaths per year making it the leading cause of death during pregnancy. About 0.4 women per 100,000 deliveries die from PPH in the United Kingdom while about 150 women per 100,000 deliveries die in sub-Saharan Africa. Rates of death have decreased substantially since at least the late 1800s in the United Kingdom. Depending on the source, primary postpartum bleeding is defined as blood loss in excess of 500 ml following vaginal delivery or 1000 ml following caesarean section in the first 24 hours following birth. Secondary postpartum bleeding is that which occurs after the first day and up to six weeks after childbirth. Symptoms generally include heavy bleeding from the vagina that doesn't slow or stop over time. Initially there may be an increased heart rate, feeling faint upon standing, and an increased respiratory rate. As more blood is lost the woman may feel cold, blood pressure may drop, and she may become unconscious. Signs of circulartory shock may also include blurry vision, cold and clammy skin, confusion, feeling sleepy or weak. Causes of postpartum hemorrhage are uterine atony, trauma, retained placenta or placental abnormalities, and coagulopathy, commonly referred to as the 'four Ts': Other risk factors include obesity, fever during pregnancy, bleeding before delivery, and heart disease.