Identification of Early Predictors of Fetomaternal Hemorrhage

Plain-language summary

Objectives: 1) To determine risk factors for fetomaternal hemorrhage. 2) To identify a cost-effective method to detect fetomaternal hemorrhage prior to significant fetal anemia. Significance/Background: Fetomaternal hemorrhage (FMH) is a condition in which occurs when the placenta transfers blood from the fetus to the mother. Normally, nutrition and gasses pass from mother to baby through the placenta and only waste products pass from baby to mother through the placenta. Whole blood cells do not normally cross the placenta in significant amounts. Mild FMH, where a small amount of whole blood passes from fetus to mother but does not hurt the mother or baby, occurs in about 75% of pregnancies. A pregnant woman does not know this occurs. It is only discovered if a special blood test that is labor-intensive to perform and difficult to interpret called the Kleihauer-Betke acid elution test is done. As mild FMH hurts no one, this test is not part of routine care. In most cases, testing is done only if a baby is born sick with unexplained anemia. Severe FMH, which can cause the baby to become sick from anemia (low red blood cell count) is caused by large blood loss into the mother, occurs in only 1-3 per 1000 births. Severe anemia caused by FMH can result in death of the baby before or after birth, or significant illness in the newborn period. Short term problems for the baby include difficulty breathing, difficulty maintaining blood pressure, and difficulty providing oxygen to all parts of the body. This can cause multiple problems with the function of internal organs including the liver, kidneys, intestines, and brain. Babies who become sick from severe FMH can develop long-term problems including cerebral palsy (a lifelong problem with body movements) and/or mental retardation. It is not known why some pregnancies are affected by FMH and others are not. It is thought that FMH may occur more frequently now than in the past, but no one knows why. If identified early, FMH is readily treatable by blood transfusion of the baby before or after birth and/or early delivery. Current laboratory testing for FMH is difficult and expensive. There is great need identify high risk patients early in pregnancy in order to treat the condition before the baby gets sick. Approach: Five hundred women will be asked to participate in the study at the time they are admitted to the Mount Sinai labor floor for delivery at term. After birth, newborns of study mothers will be tested for anemia. Mothers of anemic babies will donate blood for confirmation of FMH by established laboratory methods as well as for development of a new laboratory screening protocol. All mothers will provide medical, social, environmental, and full pregnancy history. Risk factors for FMH will be identified by statistical analysis of this information.

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