Labor is a dynamic process that involves two patients: the mother and the baby. Circumstances may arise to make labor more difficult. One problem can be the size of the baby. If the baby is too large in relation to the passage size of the birth canal, spontaneous vaginal delivery may be difficult, labor may arrest, and a cesarean section could be required. Malpresentation, when the baby is faced in any direction other than head first in the birth canal, can be another potential difficulty. Previously, a baby would often be delivered if the breech (buttocks of the baby) were coming out first. Recent data has suggested that breech babies delivered vaginally have a higher rate of complications. Currently it is standard of care to offer a cesarean section to women who are in labor and have a baby in breech position. Often, prior to labor and late in the third trimester, the obstetrician can try to turn the baby around with a procedure called external cephalic version. This procedure involves pushing on the mother's abdomen in a certain way in order to facilitate the baby's head to roll into the pelvis. This is successful about 60% of the time. It is always performed in the hospital in case the baby does not tolerate the procedure, yet this is a rare event.
Other problems with labor can be grouped into two categories: (i) those occurring during labor and (ii) those occurring during delivery.
Some issues that may arise during labor have been already discussed, however two common events that can occur are abnormalities in the baby's electronic fetal monitoring and infection in the uterus. If the baby's monitoring strip shows abnormal variation in the heart rate, the obstetrician will investigate these. Sometimes they can be due to a lack of amniotic fluid, in which case a catheter can be used to instill additional fluid (called amnioinfusion), and sometimes they can be due to the umbilical cord being wrapped around the baby's neck. Though this sounds quite serious, unless it is very tight, it generally does not cause much trouble, and the obstetrician can usually tell the cause of the abnormalities by looking at certain patterns in the monitoring strip. The doctor can also gauge how serious an umbilical cord around the neck may be by examining the fetal heart tracing closely. More serious issues arise if the placenta is not delivering enough blood to the umbilical cord. This results in a specific pattern on the monitor called late decelerations, which may require a cesarean delivery if they are persistent. Intraamniotic infections are generally treated with antibiotics during labor and after delivery for both the mother and baby. An infection can be the result of too many vaginal examinations and can often make the baby's heart rate increase, which is generally not dangerous if it doesn't persist for too long.
During delivery the baby may be a bit too large to fit through the birth canal. This does not always mean that the baby should not be delivered vaginally. In skilled hands, the use of obstetrical forceps or a vacuum can facilitate a successful delivery with minimal trauma to the baby and the mother. There are specific circumstances in which these sorts of operative deliveries are thought to be safe and a seasoned practitioner will be aware of the appropriate indications.
After delivery, the placenta usually follows readily. If it is not delivered completely, a portion could be retained within the uterus and lead to significant bleeding after delivery. If a large amount of oxytocin was used to augment labor, this too can result in excessive bleeding after delivery, termed postpartum hemorrhage. Postpartum hemorrhage occurs when the uterus doesn't contract properly after delivery. This can be due to infection, prolonged labor, retained placenta, a very rapid labor and delivery, preexisting blood clotting disorders, or trauma to the birth canal during delivery.