This happens when the collection of blood between the surface of the placenta and the uterus is trapped and does not escape through the cervix into the vagina. Sometimes, the blood forces its way into the bag of water around the baby. In this case, blood would not be seen until you break your bag of water. However, most of the time the blood makes its way down to the cervix between the bag of water and the uterine wall and is discharged into the vagina. Pain associated with an abruption can vary from mild to severe.
Contractions usually intensify the pain with an abruption.
Other signs include tenderness across your belly or if your belly feels very hard. An obvious sudden increase in the size of your belly or the onset of labor may also be worrisome signs of an abruption. Labor is nature's way of trying to correct the problem. Obviously, if the placenta is coming away from the uterine wall it is not properly transporting blood and oxygen to the baby. Therefore, the baby will experience distress and even death.