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Fetal Monitoring during Labor
You may wonder how your doctor can tell your baby is all right, especially during labor. In many hospitals, the baby's heart rate is monitored throughout labor. Being able to detect problems early is important so they can be resolved.
Every time the uterus contracts during labor, less oxygenated blood flows from you to the placenta. Most babies are able to handle this stress without any problem. However, some are affected; this is called fetal distress.

There are two ways to monitor the baby's heartbeat during labor. External fetal monitoring can be used before your membranes rupture. A belt with a receiver is strapped to your abdomen. It uses a principle similar to ultrasound to detect the baby's heartbeat.

An internal fetal monitor monitors the baby's heartbeat more precisely. An electrode is placed on the baby's scalp and is connected by wires to a machine that records the fetal heart rate. Only women whose membranes are broken and who are dilated at least lcm can be attached to an internal fetal monitor.

The Contraction Stress Test
In evaluating a fetal heart rate, a doctor looks at a large portion of the fetal monitoring strip, not just a small section. He or she also looks for other information. For example, if you are having contractions, it's important to know how your baby is affected. Fetal monitoring can help determine this.

A contraction stress test (CST) gives an indication of how well the baby will tolerate contractions and labor. If the baby doesn't respond well to contractions, it can be a sign of fetal distress. Some believe this test is more accurate than the nonstress test (discussed in Week 34) in evaluating the baby's well-being. A monitor is placed on your abdomen to monitor the baby. You are attached to an I.v. that dispenses small amounts of the hormone oxytocin to make your uterus contract.
If you've had problem pregnancies before, such as a stillbirth, or medical problems during pregnancy, such as diabetes, your healthcare provider may have you tested as you go through pregnancy. You may be tested weekly or biweekly to determine if the baby is doing well inside your uterus.

Fetal Blood Sampling
Doctors can also test your baby's blood pH to see how well your baby is tolerating the stress of labor. Before this test can be done, your membranes must be ruptured, and you must be dilated at least 2cm.
An instrument is applied to the scalp of the baby to make a small nick in the skin. The baby's blood is collected in a small tube or pipette, and its pH (acidity) is checked. If the baby is having trouble with labor and is under stress, the pH level can help determine this. This test may be useful in making a decision as to whether labor can continue or if a (-section needs to be done.

Fetal monitoring during labor can be done at home or in the hospital or birth center using ascultation, Dopplers or various forms of electronic fetal monitoring. A lot of people think that continuous fetal monitoring should be used only when there are significant risk factors for complications.