One major risk of any type of fetal monitoring is the presence of false positive and false negative results. A false positive result is when the information is interpreted as indicating distress but there is no fetal distress. This might result in a cesarean section or a delivery by forceps or vacuum. Research has shown that electronic fetal monitoring is prone to giving false positive results. A false negative result is where the information from monitoring indicates that the baby is healthy but the baby is born with problems. This type of error is less common and research is beginning to show that the majority of these babies have an underlying abnormality that began before labor and is responsible for their problems after birth.
Other minor risks of fetal monitoring may arise when internal monitoring is necessary. Internal monitoring requires a small wire to be placed beneath the skin of the baby's scalp. This results in a small break in the skin that usually heals without a problem, but in rare cases may result in bleeding or a skin infection.. To enter the uterus, the fetal scalp electrode (and the internal pressure transducer if one is used) must pass through the vagina, which is normally full of bacteria. In general, vaginal bacteria are not harmful, but placing these devices may occasionally introduce new bacteria into the uterine cavity and cause an infection called chorioamnionitis. This infection may cause fever during labor. Fortunately, chorioamnionitis is generally treatable and rarely results in any long-term negative consequences for mother or baby. It must also be emphasized that while using these devices slightly increases the risk for chorioamnionitis, it is uncertain whether the device causes the infection. The increase in infection rate could be due to the fact that internal monitors are more frequently used during long, difficult labors commonly associated with preexisting infection. In most cases, both external and internal monitors relay the same information to the birthing team.