Women with placenta previa often present with painless, bright red vaginal bleeding. This commonly occurs around 32 weeks of gestation, but can be as early as late mid-trimester. 51.6% of women with placenta previa have antepartum haemorrhage. This bleeding often starts mildly and may increase as the area of placental separation increases. Previa should be suspected if there is bleeding after 24 weeks of gestation. Bleeding after delivery occurs in about 22% of those affected.

Women may also present as a case of failure of engagement of fetal head.

Abnormal bleeding after delivery, or postpartum hemorrhage, is the loss of greater than 500 ml of blood following vaginal delivery, or 1000 ml of blood following cesarean section. Other definitions of excessive postpartum bleeding are hemodynamic instability, drop of hemoglobin of more than 10%, or requiring blood transfusion. In the literature, primary postpartum hemorrhage is defined as uncontrolled bleeding that occurs in the first 24 hours after delivery while secondary hemorrhage occurs between 24 hours and six weeks.

Obstetrical bleeding also known as obstetrical hemorrhage and maternal hemorrhage, refers to heavy bleeding during pregnancy, labor, or the postpartum period. Bleeding may be vaginal or less commonly but more dangerously, internal, into the abdominal cavity. Typically bleeding is related to the pregnancy itself, but some forms of bleeding are caused by other events.

The most frequent cause of maternal mortality worldwide is severe hemorrhage with 8.7 million cases occurring in 2015 and 83,000 of those events resulting in maternal death. Between 2003 and 2009, hemorrhage accounted for 27.1% of all maternal deaths globally

Placenta praevia is when the placenta attaches inside the uterus but near or over the cervical opening. Symptoms include vaginal bleeding in the second half of pregnancy. The bleeding is bright red and tends not to be associated with pain. Complications may include placenta accreta, dangerously low blood pressure, or bleeding after delivery. Complications for the baby may include fetal growth restriction.

Risk factors include pregnancy at an older age and smoking as well as prior cesarean section, labor induction, or termination of pregnancy. Diagnosis is by ultrasound. It is classified as a complication of pregnancy.

For those who are less than 36 weeks pregnant with only a small amount of bleeding recommendations may include bed rest and avoiding sexual intercourse. For those after 36 weeks of pregnancy or with a significant amount of bleeding, cesarean section is generally recommended. In those less than 36 weeks pregnant, corticosteroids may be given to speed development of the babies lungs. Cases that occur in early pregnancy may resolve on their own.

It affects approximately 0.5% of pregnancies. After four cesarean section it, however, effects 10% of pregnancies. Rates of disease have increased over the late 20th century and early 21st century. The condition was first described in 1685 by Paul Portal.

Symptoms of a rupture may be initially quite subtle. An old cesarean scar may undergo dehiscence; but with further labor the woman may experience abdominal pain and vaginal bleeding, though these signs are difficult to distinguish from normal labor. Often a deterioration of the fetal heart rate is a leading sign, but the cardinal sign of uterine rupture is loss of fetal station on manual vaginal exam. Intra-abdominal bleeding can lead to hypovolemic shock and death. Although the associated maternal mortality is now less than one percent, the fetal mortality rate is between two and six percent when rupture occurs in the hospital.

In pregnancy uterine rupture may cause a viable abdominal pregnancy. This is what accounts for most abdominal pregnancy births.

- Abdominal pain and tenderness. The pain may not be severe; it may occur suddenly at the peak of a contraction. The woman may describe a feeling that something "gave way" or "ripped."

- Chest pain, pain between the scapulae, or pain on inspiration—Pain occurs because of the irritation of blood below the woman's diaphragm

- Hypovolemic shock caused by haemorrhage— Falling blood pressure, tachycardia, tachypnea, pallor, cool and clammy skin, and anxiety. The fall in blood pressure is often a late sign of haemorrhage

- Signs associated with fetal oxygenation, such as late deceleration, reduced variability, tachycardia, and bradycardia

- Absent fetal heart sounds with a large disruption of the placenta; absent fetal heart activity by ultrasound examination

- Cessation of uterine contractions

- Palpation of the fetus outside the uterus (usually occurs only with a large, complete rupture). The fetus is likely to be dead at this point.

- Signs of an abdominal pregnancy

- Post-term pregnancy

Retained placenta is a condition in which all or part of the placenta or membranes remain in the uterus during the third stage of labour. Retained placenta can be broadly divided into:

- failed separation of the placenta from the uterine lining

- placenta separated from the uterine lining but retained within the uterus

A retained placenta is commonly a cause of postpartum haemorrhage, both primary and secondary.

Antepartum bleeding, also known as antepartum haemorrhage or prepartum hemorrhage, is genital bleeding during pregnancy from the 28th week (sometimes defined as from the 20th week) gestational age to term.

It can be associated with reduced fetal birth weight.

In regard to treatment, it should be considered a medical emergency (regardless of whether there is pain) and medical attention should be sought immediately, as if it is left untreated it can lead to death of the mother and/or fetus.

Hyperemesis gravidarum is the presence of severe and persistent vomiting, causing dehydration and weight loss. It is more severe than the more common morning sickness and is estimated to affect 0.5–2.0% of pregnant women.

In humans, retained placenta is generally defined as a placenta that has not undergone placental expulsion within 30 minutes of the baby’s birth where the third stage of labor has been managed actively.

Risks of retained placenta include hemorrhage and infection. After the placenta is delivered, the uterus should contract down to close off all the blood vessels inside the uterus. If the placenta only partially separates, the uterus cannot contract properly, so the blood vessels inside will continue to bleed. A retained placenta thereby leads to hemorrhage.

Perineal tearing is the spontaneous (unintended) tearing of the skin and other soft tissue structures which, in women, separate the vagina from the anus. Perineal tearing occurs in 85% of vaginal deliveries. At 6 months postpartum, 21% of women still report perineal pain and 11-49% report sexual problems or painful intercourse.

Uterine rupture is a serious event during childbirth by which the integrity of the myometrial wall is breached. In an incomplete rupture the peritoneum is still intact. With a complete rupture the contents of the uterus may spill into the peritoneal cavity or the broad ligament. A uterine rupture is a life-threatening event for mother and baby.

A uterine rupture typically occurs during active labor, but may also develop during late pregnancy.

Uterine dehiscence is a similar condition, but involves fewer layers, less bleeding, and less risk.

Placenta accreta occurs when all or part of the placenta attaches abnormally to the myometrium (the muscular layer of the uterine wall). Three grades of abnormal placental attachment are defined according to the depth of attachment and invasion into the muscular layers of the uterus:

- Accreta – chorionic villi attach to the myometrium, rather than being restricted within the decidua basalis.

- Increta – chorionic villi invade into the myometrium.

- Percreta – chorionic villi invade through the perimetrium (uterine serosa).

Because of abnormal attachment to the myometrium, placenta accreta is associated with an increased risk of heavy bleeding at the time of attempted vaginal delivery. The need for transfusion of blood products is frequent, and hysterectomy is sometimes required to control life-threatening hemorrhage.

When the antepartum diagnosis of placenta accreta is made, it is usually based on ultrasound findings in the second or third trimester. Sonographic findings that may be suggestive of placenta accreta include:

1. Loss of normal hypoechoic retroplacental zone

2. Multiple vascular lacunae (irregular vascular spaces) within placenta, giving "Swiss cheese" appearance

3. Blood vessels or placental tissue bridging uterine-placental margin, myometrial-bladder interface, or crossing the uterine serosa

4. Retroplacental myometrial thickness of <1 mm

5. Numerous coherent vessels visualized with 3-dimensional power Doppler in basal view

Although there are isolated case reports of placenta accreta being diagnosed in the first trimester or at the time of abortion <20 weeks' gestational age, the predictive value of first-trimester ultrasound for this diagnosis remains unknown. Women with a placenta previa or "low-lying placenta" overlying a uterine scar early in pregnancy should undergo follow-up imaging in the third trimester with attention to the potential presence of placenta accreta.

Hypercoagulability in pregnancy is the propensity of pregnant women to develop thrombosis (blood clots). Pregnancy itself is a factor of hypercoagulability (pregnancy-induced hypercoagulability), as a physiologically adaptive mechanism to prevent "post partum" bleeding. However, when combined with an additional underlying hypercoagulable states, the risk of thrombosis or embolism may become substantial.

The seizures of eclampsia typically present during pregnancy and prior to delivery (the antepartum period), but may also occur during labor and delivery (the intrapartum period) or after the baby has been delivered (the postpartum period). If postpartum seizures develop, it is most likely to occur within the first 48 hours after delivery. However, late postpartum seizures of eclampsia may occur as late as 4 weeks after delivery.

Pregnancy-induced hypercoagulability is probably a physiologically adaptive mechanism to prevent "post partum" hemorrhage. Pregnancy changes the plasma levels of many clotting factors, such as fibrinogen, which can rise up to three times its normal value. Thrombin levels increase. Protein S, an anticoagulant, decreases. However, the other major anticoagulants, protein C and antithrombin III, remain constant. Fibrinolysis is impaired by an increase in plasminogen activator inhibitor-1 (PAI-1 or PAI) and plasminogen activator inhibitor-2 (PAI-2), the latter synthesized from the placenta. Venous stasis may occur at the end of the first trimester, due to enhanced compliance of the vessel walls by a hormonal effect.

Also, pregnancy can cause hypercoagulability by other factors, e.g. the prolonged bed rest that often occurs "post partum" that occurs in case of delivery by forceps, vacuum extractor or Caesarean section.

A study of more than 200,000 women came to the result that admission to inpatient care during pregnancy was associated with an 18-fold increase in the risk of venous thromboembolism (VTE) during the stay, and a 6-fold increase in risk in the four weeks after discharge, compared with pregnant women who did not require hospitalization. The study included women admitted to hospital for one or more days for reasons other than delivery or venous thromboembolism.

Pregnancy after the age of 35 augments the risk of VTE, as does multigravidity of more than four pregnancies.

Pregnancy in itself causes approximately a five-fold increased risk of deep venous thrombosis. Several pregnancy complications, such as pre-eclampsia, cause substantial hypercoagulability.

Hypercoagulability states as a pre-existing condition in pregnancy include both acquired ones, such as antiphospholipid antibodies, and congenital ones, including factor V Leiden, prothrombin mutation, proteins C and S deficiencies, and antithrombin III deficiency.

Both are composed of intermediate trophoblast, but their morphological features and clinical presentation can differ significantly.

Exaggerated placental site is a benign, non cancerous lesion with an increased number of implantation site intermediate trophoblastic cells that infiltrate the endometrium and the underlying myometrium. An exaggerated placental site may occur with normal pregnancy, or after an abortion. No specific treatment or follow up is necessary.

Placental site nodules are lesions of chorionic type intermediate trophoblast, usually small. 40 to 50% of placental site nodules are found in the cervix. They almost always are incidental findings after a surgical procedure. No specific treatment or follow up is necessary.

Eclampsia is a disorder of pregnancy characterized by seizures in the setting of pre-eclampsia. Typically the pregnant woman develops hypertension and proteinuria before the onset of a convulsion (seizure).

- Long-lasting (persistent) headaches

- Blurry vision

- Photophobia (i.e. bright light causes discomfort)

- Abdominal pain

- Either in the epigastric region (the center of the abdomen above the navel, or belly-button)

- And/or in the right upper quadrant of the abdomen (below the right side of the rib cage)

- Altered mental status (confusion)

Any of these symptoms may present before or after a seizure occurs. It is also possible that none of these symptoms will develop.

Other cerebral signs may immediately precede the convulsion, such as nausea, vomiting, headaches, and cortical blindness. If the complication of multi-organ failure ensues, signs and symptoms of those failing organs will appear, such as abdominal pain, jaundice, shortness of breath, and diminished urine output.

HELLP usually begins during the third trimester; rare cases have been reported as early as 21 weeks gestation. Often, a woman who develops HELLP syndrome has already been followed up for pregnancy-induced hypertension (gestational hypertension), or is suspected to develop pre-eclampsia (high blood pressure and proteinuria). Up to 8% of all cases occur after delivery.

Women with HELLP syndrome often appear non-toxic. Early symptoms can include:

- In 90% of cases, either epigastric pain described as "heartburn" or right upper quadrant pain develops.

- In 90% of cases, malaise occurs.

- In 50% of cases, nausea or vomiting happen.

Gradual but marked onset of headaches (30%), blurred vision, and paresthesia (tingling in the extremities) can occur. Edema may occur, but its absence does not exclude HELLP syndrome. Arterial hypertension is a diagnostic requirement, but may be mild. Rupture of the liver capsule and a resultant hematoma may occur. If a woman has a seizure or coma, the condition has progressed into full-blown eclampsia.

Disseminated intravascular coagulation is also seen in about 20% of all women with HELLP syndrome, and in 84% when HELLP is complicated by acute renal failure. Pulmonary edema is found in 6% of all women with HELLP syndrome, and when HELLP is complicated by acute renal failure, pulmonary edema is found in 44% of women with the syndrome.

A woman with symptoms of HELLP can be misdiagnosed in the early stages, increasing the risk of liver failure and morbidity. Rarely, after a caesarean section surgery, a woman may have signs and symptoms of a shock condition mimicking either pulmonary embolism or reactionary haemorrhage.

Fetal-maternal haemorrhage is the loss of fetal blood cells into the maternal circulation. It takes place in normal pregnancies as well as when there are obstetric or trauma related complications to pregnancy.

Normally the maternal circulation and the fetal circulation are kept from direct contact with each other, with gas and nutrient exchange taking place across a membrane in the placenta made of two layers, the syncytiotrophoblast and the cytotrophoblast. Fetal-maternal haemorrhage occurs when this membrane ceases to function as a barrier and fetal cells may come in contact with and enter the maternal vessels in the decidua/endometrium.

In some very rare cases, a GTD can coexist with a normal fetus. This is called a "twin pregnancy". These cases should be managed only by experienced clinics, after extensive consultation with the patient. Because successful term delivery might be possible, the pregnancy should be allowed to proceed if the mother wishes, following appropriate counselling. The probability of achieving a healthy baby is approximately 40%, but there is a risk of complications, e.g. pulmonary embolism and pre-eclampsia. Compared with women who simply had a GTD in the past, there is no increased risk of developing persistent GTD after such a twin pregnancy.

In few cases, a GTD had coexisted with a normal pregnancy, but this was discovered only incidentally after a normal birth.

Causes of increased foetal-maternal haemorrhage are seen as a result of trauma, placental abruption or may be spontaneous with no cause found.

Up to 30 mL of foetal-maternal transfusion may take place with no significant signs or symptoms seen in either mother or foetus. Loss in excess of this may result in significant morbidity and mortality to the fetus. Foetal-maternal haemorrhage is one cause of intrauterine death (IUD).

Arterial occlusion may be due to thrombi, amniotic fragments or air embolism. Postpartum cerebral angiopathy is a transitory arterial spasm of medium caliber cerebral arteries; it was first described in cocaine and amphetamine addicts, but can also complicate ergot and bromocriptine prescribed to inhibit lactation. Subarachnoid haemorrhage can occur after miscarriage or childbirth. Epidural anaesthesia can, if the dura is punctured, lead to leakage of Cerebrospinal fluid and subdural haematoma. All these can occasionally present with psychiatric symptoms.

HELLP syndrome is a life-threatening pregnancy complication usually considered to be a variant or complication of pre-eclampsia. Both conditions usually occur during the later stages of pregnancy, or sometimes after childbirth. "HELLP" is an abbreviation of the three main features of the syndrome: Hemolysis, Elevated Liver enzymes, and Low Platelet count. The syndrome may be associated with serious liver manifestations, including death of liver cells due to inadequate blood flow and oxygen delivery, bleeding, and rupture.

Perinatal mortality (PNM), also perinatal death, refers to the death of a fetus or neonate and is the basis to calculate the perinatal mortality rate. Variations in the precise definition of the perinatal mortality exist specifically concerning the issue of inclusion or exclusion of early fetal and late neonatal fatalities. The World Health Organization defines perinatal mortality as the "number of stillbirths and deaths in the first week of life per 1,000 total births, the perinatal period commences at 22 completed weeks (154 days) of gestation and ends seven completed days after birth", but other definitions have been used.

The UK figure is about 8 per 1,000 and varies markedly by social class with the highest rates seen in Asian women. Globally about 2.6 million neonates died in 2013 before the first month of age down from 4.5 million in 1990.