The most common medications used systemically are relatives of the narcotic morphine — drugs such as meperidine (brand name Demerol), fentanyl (Sublimaze), butorphanal (Stadol), and nalbuphine (Nubain). These medications can be given every two to four hours as needed, either intravenously or intramuscularly.
Any medication you take (even when you’re not pregnant) has side effects, and pain relievers used during labor are no exception, although your doctor will do what he can to reduce these side effects, often by combining medications. Nausea, vomiting, drowsiness, and a drop in your blood pressure are the main side effects for the mother.
The degree to which the fetus or newborn is also affected depends on how close to the time of delivery the medication is given. If a large dose is given within two hours prior to delivery, the newborn may be sleepy or groggy.
In rare cases, his breathing may be weak. If this problem is significant, your doctor or the baby’s doctor can give a medication that immediately reverses or counteracts the pain medication.
No evidence suggests that these medications, when given in appropriate doses and with proper monitoring, have any effect on the progress of labor or on the rate of cesarean deliveries.