Drugs for labour

Drugs for labour are used to prevent or start labour or for associated problems.

Drugs may be used during labour, either as a routine part of medical care or to treat specific problems. Among the most commonly used drugs during childbirth are epidural anaesthetics (see Epidural anaesthesia in labour).

It may be necessary to use drugs to induce labour (start labour artificially) if the health of the mother or the fetus is at risk. The most common reasons for the induction of labour include continuation of pregnancy beyond the due delivery date or complications, such as poor growth of the baby. Drugs may also be given to speed up labour if it does not progress as quickly as it should or to prevent bleeding after delivery.

If labour starts early (before the 34th week of pregnancy), drugs are often used to stop or delay delivery.

Common drugs

Uterine stimulant drugs: Carboprost, Dinoprostone, Ergometrine, Gemeprost, Oxytocin	Uterine muscle relaxant drugs: Salbutamol, Ritodrine, Terbutaline
Magnesium:

What are the types of drugs for labour?

Drugs are used during labour either to stimulate contractions of the uterus or to relax the uterus. The most commonly used drugs are known as uterine stimulants. These drugs induce labour by starting contractions or speed up labour by strengthening contractions. Uterine stimulants may also be used for the termination of pregnancy. Drugs that relax the uterus to delay premature labour are called uterine muscle relaxants. Magnesium may be used to prevent seizures during labour in women with the condition pre-eclampsia (see Pre-eclampsia and eclampsia).

Uterine stimulant drugs

If labour is going to be induced or if it is necessary to terminate pregnancy, a pessary that contains a prostaglandin uterine stimulant may be inserted into the vagina. Prostaglandins not only stimulate contractions but also soften and widen the cervix. Prostaglandins may also be administered in the form of gel. During treatment with a prostaglandin, you may occasionally experience some side effects, such as nausea, vomiting, diarrhoea, and hot flushes.

Oxytocin, another uterine stimulant, is given by infusion into a vein to induce labour or to speed up prolonged labour by increasing the strength, duration, and frequency of contractions. The dose will be adjusted carefully, as excess oxytocin may result in painful, continuous contractions, nausea, vomiting, and fluid retention.

A combination of oxytocin and ergometrine, another uterine stimulant drug, is given by intramuscular injection to most women just as the baby is delivered. The drugs cause strong uterine contractions that hasten delivery of the placenta and also constrict the blood vessels in the uterus to reduce bleeding after delivery. A common side effect of ergometrine is nausea. In rare cases, headache, light-headedness, and ringing in the ears may occur.

Uterine muscle relaxant drugs

If labour begins prematurely, the doctor may give you drugs, such as ritodrine or terbutaline, to relax the muscles of your uterus, thereby preventing further contractions. Uterine muscle relaxants are given continuously by infusion into a vein. However, even with this method of administration, the drugs often become less effective after about 48 hours. Uterine muscle relaxants may have side effects such as nausea, hot flushes, and rapid heartbeat; your blood pressure may drop, causing light-headedness.

Magnesium

This mineral may be used to prevent seizures that can occur during labour in women with pre-eclampsia. It may also be used to try to stop premature labour, especially in multiple pregnancy. Side effects may include flushing, sweating, and low blood pressure.

BMA Complete Family Health Guide Copyright © 2005 Dorling Kindersley

Posted 09.09.2010

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