If labor does not proceed normally, the fetus or newborn may have problems.
Fetal distress refers to signs before and during childbirth indicating that the fetus is not well.
Fetal distress is an uncommon complication of labor. It typically occurs when the fetus has not been receiving enough oxygen. Fetal distress may occur when the pregnancy lasts too long (postmaturity) or when complications of pregnancy or labor occur.
Usually, doctors identify fetal distress based on an abnormal heart rate pattern in the fetus. Throughout labor, the fetus's heart rate is monitored. It is usually monitored continuously with electronic fetal heart monitoring. Or, a handheld Doppler ultrasound device may be used to check the heart rate every 15 minutes during early labor and after each contraction during late labor.
If a significant abnormality in the heart rate is detected, it can usually be corrected by the following:
If these measures are not effective, the baby is delivered as quickly as possible by a vacuum extractor, forceps, or cesarean delivery.
If the amniotic fluid appears green after the membranes have ruptured, the fetus may be in distress (but usually is not). This discoloration is caused by the fetus's first stool (called meconium). Meconium can sometimes be inhaled before labor or during delivery, causing the baby to have difficulty breathing shortly after birth.
Rarely, a baby does not start to breathe at birth, even though no problems were detected before delivery. Then the baby requires resuscitation. Personnel skilled in resuscitating babies may attend the delivery for this reason.
Abnormal Position and Presentation of the Fetus
Position refers to whether the fetus is facing rearward (toward the woman's back, or face down when the woman lies on her back) or forward (face up). Presentation refers to the part of the fetus's body that leads the way out through the birth canal. The most common and safest combination consists of the following:
If the fetus is in a different position or presentation, labor may be more difficult and delivery through the vagina may not be possible.
When a fetus faces forward (an abnormal position), the neck is often straightened rather than bent, and the head requires more space to pass through the birth canal. Delivery by a vacuum extractor or forceps or cesarean delivery may be necessary.
There are several abnormal presentations.
The buttocks present first. Breech presentation occurs in 2 to 3% of full-term deliveries. When delivered vaginally, babies that present buttocks first are more likely to be injured than those that present head first. Such injuries may occur before, during, or after birth and include death. Complications are less likely when breech presentation is detected before labor or delivery.
Sometimes the doctor can turn the fetus to present head first by pressing on the woman's abdomen before labor begins, usually at the 37th or 38th week of pregnancy. However, if labor begins and the fetus is in breech presentation, problems may occur. The passageway made by the buttocks in the birth canal may not be large enough for the head (which is wider) to pass through. In addition, when the head follows the buttocks, it cannot be molded to fit through the birth canal, as it normally is. Thus, the baby's body may be delivered and the head may be caught inside the woman. As a result, the spinal cord or other nerves may be stretched, leading to nerve damage. When the baby's navel is first seen outside the woman, the umbilical cord is compressed between the baby's head and the birth canal, so that very little oxygen can reach the baby. Brain damage due to lack of oxygen is more common among babies presenting buttocks first than among those presenting head first. In a first delivery, these problems are worse because the woman's tissues have not been stretched by previous deliveries. Because the baby could be injured or die, cesarean delivery is preferred when the fetus is in breech presentation.
In face presentation, the neck arches back so that the face presents first. In brow presentation, the neck is moderately arched so that the brow presents first. Usually, fetuses do not stay in a face or brow presentation. They often correct themselves. If they do not, forceps, vacuum extractor, or cesarean delivery may be used.
Occasionally, a fetus lying horizontally (transversely) across the birth canal presents shoulder first. A cesarean delivery is done, unless the fetus is the second in a set of twins. In such a case, the fetus may be turned to be delivered through the vagina.
The term multiple births refers to the presence of more than one fetus in the uterus.
The number of twin, triplet, and other multiple births has been increasing during the last two decades. About 1 of 70 to 80 deliveries involves more than one fetus. The following make women more likely to become pregnant with more than one fetus:
Carrying more than one fetus overstretches the uterus, and an overstretched uterus tends to start contracting before the pregnancy reaches full term. As a result, the babies are usually born prematurely and are small. In some cases, the overstretched uterus does not contract well after delivery, causing bleeding in the woman after delivery. Because the fetuses can be in various positions and presentations, vaginal delivery can be complicated. Also, the contraction of the uterus after delivery of the first baby may shear away the placenta of the remaining baby or babies. As a result, the baby or babies that follow the first may have more problems during delivery.
Carrying more than one fetus also increases the risk of problems for the woman. They include high blood pressure plus protein in the urine (preeclampsia), gestational diabetes, excessive bleeding at delivery (postpartum hemorrhage), the need for cesarean delivery, small newborns (growth restriction), and preterm delivery.
During pregnancy, ultrasonography is done to confirm the number of fetuses.
Because problems can result from multiple births, doctors may decide in advance whether to deliver twins vaginally or by cesarean. If the first twin is in an abnormal position (anything other than head first), cesarean delivery is used. Occasionally, the first twin is delivered vaginally, but a cesarean delivery is considered safer for the second twin. For triplets and other multiple births, a cesarean delivery is usually done.
Shoulder dystocia occurs when one shoulder of the fetus lodges against the woman's pubic bone, and the baby is therefore caught in the birth canal.
Because the fetus's shoulder is lodged against the woman's pubic bone, the fetus's head comes out, but it is pulled back tightly against the vaginal opening. The baby cannot breathe because the chest and umbilical cord are compressed by the birth canal. As a result, oxygen levels in the baby's blood decrease. Shoulder dystocia is more common with large fetuses, particularly when labor is difficult or when a vacuum extractor or forceps is used because the fetus's head has not fully moved down (descended) in the pelvis. It is also more common when women are obese, have diabetes, or have had a previous baby with shoulder dystocia.
When this complication occurs, the doctor quickly tries various techniques to free the shoulder so that the baby can be delivered vaginally. Sometimes when these techniques are tried, the baby's nerves are damaged or the baby's arm bone or collarbone may be broken. An episiotomy (an incision that widens the opening of the vagina) may be done to help with delivery. If these techniques are unsuccessful, the baby may be pushed back into the vagina and delivered by cesarean.
Prolapsed Umbilical Cord
Prolapse of the umbilical cord means that the cord precedes the baby through the vagina.
A prolapsed umbilical cord occurs in about 1 of 1,000 deliveries. When the umbilical cord prolapses, the fetus's body may put pressure on the cord and thus cut off the fetus's blood supply. This uncommon complication may be obvious (overt) or not (occult).
The membranes have ruptured, and the umbilical cord protrudes into or out of the vagina before the baby emerges. Overt prolapse usually occurs when a baby emerges feet or buttocks first (breech presentation). But it can occur when the baby emerges head first, particularly if the membranes rupture prematurely or the fetus has not moved down into the woman's pelvis. If the fetus has not moved down, the rush of fluid as the membranes rupture can carry the cord out ahead of the fetus.
If the cord prolapses, cesarean delivery must be done immediately to prevent the blood supply to the fetus from being cut off. Until surgery begins, a nurse or doctor holds the fetus's body off the cord so that the blood supply through the prolapsed cord is not cut off.
The membranes are intact, and the cord is in front of the fetus or trapped in front of the fetus's shoulder. Usually, occult prolapse can be identified by an abnormal pattern in the fetus's heart rate. Changing the woman's position usually corrects the problem. Occasionally, a cesarean delivery is necessary.
A nuchal cord is an umbilical cord that is wrapped around the fetus's neck.
A nuchal cord occurs in about one fourth of deliveries. Normally, the baby is not harmed.
Before birth, a nuchal cord can sometimes be detected by ultrasonography, but no action is required. Doctors routinely check for it as they deliver the baby. If they feel it, they can slip the cord over the baby's head. Sometimes if the cord is tightly wrapped, it is clamped and cut before the shoulders are delivered.
Last full review/revision December 2008 by Julie S. Moldenhauer, MD