Can Epidurals Slow Down Labour?
Epidurals are the most common pain relief used during labour, with about half of all women opting for this type of anaesthesia.
Women who want an epidural are often encouraged to wait until they are in active labour – around 5cms dilated. It has long been known that epidurals prolong the second stage of labour, also known as the pushing stage.
A recent study has shown the time added to labour by the use of epidurals might be much more than originally thought.
It was previously believed epidurals lengthened labour by about one hour. Researchers looked at more than 42 000 women in California who gave birth vaginally between 1976 and 2008, and compared the length of the second stage of labour in women who had received epidurals with those who hadn’t.
In the study, women who were having a baby for the first time with an epidural in place took almost 2.5 hours longer to go through second stage than women without an epidural.
Women who had given birth before with an epidural in place took almost 3 hours longer to get through second stage than women without an epidural.
This information could have a significant impact on the number of women who will have a c-section after having an epidural placed. Often a c-section is performed because care providers decide labour is taking too long. If an epidural is in place, women might be given more time for the second stage, and therefore avoid having surgery.
It is not known exactly how epidurals prolong labour but there are several theories. Epidurals can interfere with the release of oxytocin, the hormone responsible for effective and strong uterine contractions. During the second stage of labour, the uterus is pushing down on the baby with strong contractions, moving the baby through the completely dilated cervix and into the birth canal.
When an epidural is in place, the descent of the baby is significantly slower, compared with when there is no epidural.
It is also possible the anaesthetic medication used causes muscles to relax, and numbs vital nerves in the pelvis. While the baby is descending through the vagina, nerves are triggered; they send messages to the brain to release large surges of oxytocin. This stimulates the Ferguson’s reflex, which is the uncontrollable expulsion of the baby in two or three strong contractions.
If these nerves can’t send their messages to the brain, the baby’s descent is delayed, and the mother might need to push forcefully with each contraction. This takes a lot of energy and could contribute to an even slower second stage.
Choosing to have an epidural is a very personal decision. Many women wish to have the option of an epidural during labour, but should be aware of the possibility of labour being longer than what is considered normal – especially during the second stage. Make sure your care provider is aware of the risks of epidurals prolonging labour, to avoid the cascade of intervention which might lead to c-section.