Chemical Anaesthetics

Find out your options of chemical anaesthetics and their effects to assist pain management during labour.


Pethidine is a powerful sedative drug given by intra-muscular injection, usually into the buttocks. This takes effect within 15 minutes and can last anything from two to four hours. A common side effect is nausea, and sensations of feeling woozy, detached and disoriented.

Often pethidine is combined with an antihistamine to prevent sickness and at times this can amplify wooziness. Some women hallucinate and feel completely out of control. Some analgesic drugs are not recommended for asthma sufferers as breathing can be adversely affected.

Pethidine can drug the baby too, especially if it is administered within five hours before delivery. Although if used within 45 minutes before birth, pethidine is unlikely to have built up in the baby’s system.

Some research suggests that opiate or barbiturate drugs used in childbirth may increase the risk of addiction problems later in the baby’s life.


Called an epidural nerve block, this is a drug injected directly into the dura, the outer membrane around the spinal chord.

Epidurals are performed by a trained anaesthetist and take about half an hour to set up. It can provide complete pain relief from the waist down, while allowing you to stay conscious, and can be used as an anaesthetic for a Caesarean section.

Epidurals should not be used if there is abnormally low blood pressure, bleeding from the placenta or anticoagulants are being administered.

An epidural lowers blood pressure and at times other drugs have to be given to counteract this, sometimes causing unwanted side effects. It is important to know that not all epidurals work and complications may occur.

Dosages and techniques vary and women respond differently. Sometimes, the point of injection may need recorrecting, and you will know this as you may feel anaesthetised on one side of your body only. In such a case, the anaesthetist will adjust the insertion point.

Having an epidural may be the onset of a series of other procedures you were not expecting. As it tends to prolong labour, you may be given oxytocin and require continuous foetal monitoring. Without sensation in the lower body, you may lose bladder control and need assistance via a catheter. You may also lose the urge to push and may require forceps or a vacuum extractor delivery.

Your temperature could rise in which case more investigations may be done to ensure you and your baby are not suffering from an infection in which case your baby may be placed under special observation after the birth. There is also an increased risk of having a Caesarean section. After giving birth, many women cannot walk for a few hours, even to the bathroom or shower to clean up.

Research indicates that epidurals may be linked to mother’s post-natal problems such as back ache, migraine and neck ache. On the positive side, many women declare they could not have given birth without an epidural.

Gas & Air

Called entonox, it is a 50/50 mix of oxygen and nitrous oxide (laughing gas). Inhaled through a mask to the face, entonox takes about 30 seconds to be effective. It does not entirely relieve the pain but produces analgesic effects enough to relieve pain during the peak of the contraction. Timing is important and the mask must fit firmly against to face to prevent leakage.

It is believed the entonox does not harm the baby and is cleared from the baby’s system with the first breaths it takes at birth.


Tranquillisers may be given to reduce nausea, vomiting and anxiety. The most common is benzodiazephines, also known as Valium. It is known to adversely affect the baby’s breathing, change the baby’s heart rate, interfere with a newborn’s temperature control and cause floppiness. Often a baby affected by Valium is slow to suck. It is also thought the Valium reduces a woman’s ability to recall the labour and birth.

This drug is no longer administered to women during labour in the United States, due to the adverse effects on the baby.


Occasionally if there is an emergency situation, it is necessary to have a general anaesthetic. This is usually a low dose as to not affect the baby and so you are only unconscious for a few minutes. It is possible to have your partner in the room and arrange for your partner to hold the baby following birth.

A spinal anaesthesia is an injection into the cerebrospinal fluid in the lower spine to numb from the waist to the knees. It takes effect within five minutes and is therefore useful when time is short. Spinals are considered potentially dangerous because the blood pressure drops, reducing oxygen supply to the baby. It is advisable to lie flat and avoid lifting the head quickly for eight hours following delivery to avoid a post-spinal headache.

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