Labor is a painful experience. Many women in labor receive some sort of medication; medical practitioners in obstetrics are always aware that they have two patients and that both will be affected by any drugs given in labor. Common medications administered to laboring women include epidural anesthesia, intravenous anesthesia and paracervical blocks. Medications given during labor cross the placenta and can have negative effects on the fetus.
Intravenous Anesthesia
Intravenous (IV) medications are often used in early labor. One of the main effects of IV anesthesia is respiratory depression; newborns may not breathe if narcotics or synthetic narcotics such as Demerol, Fentanyl, morphine or Nubain are still in their system at the time of delivery. Fentanyl stays in the system only an hour, but morphine and Nubain can remain as long as 6 hours. For this reason, obstetricians try not to give IV anesthesia when delivery will occur within the next few hours, although some newborns deliver more rapidly than expected.
The fetal monitoring strip after IV anesthesia may show a decrease in accelerations of the heart rate and a loss of beat to beat variability; accelerations and variability in the fetal heartbeat indicate fetal well being. If the newborn has respiratory depression after a narcotic was given in labor, Narcan, a drug that reverses the effects of narcotics, can be given, along with supplemental oxygen and ventilation if necessary.
Epidural Anesthesia
Epidurals are regional anesthesia, where drugs are injected into the epidural space near the spine to block pain in the nerves. Janyne Althaus. M.D and Joseph Wax, M.D. of Johns Hopkins Hospital, in an article published in 2005 in "Obstetrical Gynecology Clinics of North America," state that 50 percent of American women have epidural anesthesia during labor and as many as 98 percent are given epidurals in some parts of Europe.
Both narcotics and anesthetics are injected into the epidural space. Regional anesthetics may slow labor and increase the rate of labor augmentation with Pitocin, Wax and Althaus state, and a clinical trial reported in "Obstetrics and Gynecology " by lead author Karen Cristine Abrao, M.D. calls non-reassuring fetal heart tracings such as bradycardia, or low heart rate, and decelerations, or temporary drops in heart rate. Epidural anesthesia may also cause maternal fever, which may lead to fetal tachycardia, or rapid heart rate and to an increased rate in Cesarean delivery. Causes of fever are not related to infection, according to Holger Eltzschig, M.D., lead author of an article published in the New England Journal of Medicine in 2003, and need further investigation.
Paracervical Block
A paracervical block numbs the cervix with a local anesthetic so that pain isn't felt during dilation. The main fetal effect is bradycardia, which can be severe, Althaus and Wax state. Fetal bradycardia occurs in 15 percent of cases and can result in fetal death.
References
- "New England Journal of Medicine: Regional Anesthesia and analgesia for labor and delivery;" Holger Elzschig, M.D. 2003
- "Obstetric and Gynecology: Elevation of uterine basal tone and fetal heartrate abnormalities;" KC Abrao, M.D. et al 2009
- "Obstetrics and Gynecology Clinics, North America: Analgesia and anesthesia in labor;" Janyne Althaus, M.D. Joseph Wax, M.D. Johns Hopkins Hospital; 2005
