McKesson Clinical Reference Systems: Women's Health Advisor 2002.2

What is nonreassuring fetal status?

Nonreassuring fetal status (NFS) is a term your health care provider may use to describe his or her interpretation of findings regarding your baby during labor. For example, your provider may be concerned about your baby's abnormal heart rate. Heart rate patterns may be too slow, too fast, or irregular and may mean that the baby is having some type of problem. However, an abnormal heart rate does not always mean there is a problem with the baby.

NFS may also be discovered from tests of the baby late in pregnancy, for example, from a biophysical profile.

How does it occur?

The baby gets oxygen from the mother's blood as the blood passes through the placenta. Any situation that reduces the amount of blood the baby receives may cause NFS. NFS can occur in the following situations:

• The mother's contractions are too strong, too long, or too frequent. Sometimes this may result from the use of oxytocin to help labor.
• The mother has been given local or regional anesthesia. The anesthetic may get into the mother's bloodstream and may lower her blood pressure. This may reduce the supply of blood and oxygen to the baby.
• The placenta does not function properly.
• The umbilical cord is pinched or flattened, causing blood flow to the placenta to decrease or stop.

What are the symptoms?

The mother usually has no symptoms. The following signs may mean that the baby is not getting enough oxygen:

• The baby has an abnormal heart rate.
• The baby's stool (meconium) is found in the amniotic fluid discharged from the vagina when the membranes (bag of waters) have ruptured.
• A test of blood from the baby's scalp shows that the baby's blood is too acidic.

How is it diagnosed?

To check the baby's condition, the doctor may use the following procedures and tests during labor:

• External or internal monitoring: A monitor is attached to the mother or the baby to record the baby's heart rate. Also a pressure catheter may be used to measure the strength, length, and frequency of the mother's contractions.
• Fetal scalp sampling: A sample of blood from the baby's scalp is tested to determine the acidity of the blood. If the baby is not getting enough oxygen, the blood becomes highly acidic.

The doctor may perform a vaginal exam to see if the umbilical cord has dropped into the vagina.

An abnormal heart rate does not always mean that the baby is having a problem. Sometimes when the baby's head is compressed during a contraction or delivery, the baby will have a reflex that causes the heart rate to change. The delivery team will monitor the heart rate continuously to see if the change is really a sign of fetal problems.

How is it treated?

The goal of therapy is to increase the amount of oxygen the baby is getting. If your unborn baby shows signs of NFS, the following may be done to try to increase your oxygen level and improve blood flow to the uterus:

• The doctor may ask you to lie on your left side. The large blood vessels near the spine are less likely to be flattened by the uterus in this position.
• The doctor may give you intravenous (IV) fluids or blood if your blood pressure drops during labor or if you are bleeding a lot.
• The doctor may give you oxygen through a mask so more oxygen can get to the baby.
• If oxytocin is being used to induce or assist with the progress of labor, it will be stopped or reduced if the baby's heart rate is abnormal. The contractions may be too close together or too long, preventing enough oxygen from reaching the baby.
• If the contractions are too strong or very close together, the doctor may give you medication to relax the uterus.
• If the baby's heart rate shows that the umbilical cord may be flattened with contractions, the nurse or doctor may ask you to change your position. Raising the foot of the bed or getting on your hands and knees may help get the baby off the umbilical cord.

If these treatments don't correct the problem, a cesarean delivery may be done right away to deliver the baby. Immediate vaginal delivery with forceps or a vacuum extractor may be possible if the baby is far enough down in the vagina and the cervix is completely dilated. A cesarean delivery will be necessary if your cervix isn't completely dilated.

The newborn will be examined immediately. Close observation in the nursery or intensive care nursery may be necessary if the distress was severe.

How long will the effects last?

Most babies diagnosed with NFS have no noticeable effects after birth. However, severe prolonged loss of oxygen can harm babies. The damage may be mild, resulting in learning disabilities, for example. Severe damage may result in cerebral palsy, mental retardation, or even death.

What can be done to help prevent fetal problems causing NFS?

Some fetal problems may be prevented by careful management of the mother and baby during labor and delivery and by identification of high-risk pregnancies. However, not all fetal problems can be prevented.

This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.