Investigating anaesthesia for c-sections in obese mothers

C-sections for obese mothers can be more complicated and take longer than expected. This can make it difficult to predict what type of anaesthetic should be used – particularly in emergencies. Our researchers are gathering data to help doctors pick the best type of anaesthesia to keep both mother and baby safe.
  • Author's list

    Dr Julia Critchley, Professor Fiona Denison, Dr Nazir Lone, Dr Arlene Wise

    Start date: April 2019
    End date: March 2021

  • Research centre

  • Research status

    Ongoing projects

Why do we need this research?

During a caesarean section, the mother needs anaesthesia to avoid pain. There are lots of different ways that this can be given. These include general anaesthesia, where she is fully unconscious, or a regional anaesthetic such as an epidural or spinal injection, where only one part of the body is numbed.

Using general anaesthesia during a caesarean section can be risky for both mother and baby, so anaesthetists would prefer to avoid it. However, for obese women, caesarean sections can be more complicated and take longer than expected. This means that women who had a spinal anaesthetic might end up needing a general anaesthetic part way through their surgery, as the spinal cannot be extended once it has worn off. Also, in emergencies, general anaesthesia may be the only option, as it tends to act quicker.

Right now, we don’t know for certain what the best type of anaesthetic is for obese mothers having a caesarean section. This means that mothers might receive anaesthetic that isn’t appropriate for them, which could cause problems for them and their babies.

What’s happening in this project?

In this study, Tommy’s researchers have gathered data on thousands of caesarean section surgeries taking place in and around Edinburgh between 2011 and 2018. For each one, the team have collected data on the age and BMI of the mother, how long the surgery took, what kind of anaesthetic was used, and whether it was an emergency operation or not.

So far, the team have confirmed that the time taken to give anaesthesia and perform the surgery increases as BMI increases. In women with a BMI greater than 50, surgery took around one hour. These women may therefore benefit from having an epidural inserted at the time of their spinal injection, as this would allow the anaesthetic to be topped up once the spinal had started to wear off and avoid the need for a general anaesthetic.

The researchers also found that in emergency caesarean sections, topping up an epidural prior to surgery is almost as fast as a general anaesthetic. As an epidural is considered to be safer than a general anaesthetic, this is particularly important. It suggests that obese mothers may benefit from having an epidural during labour, which could simply be topped up in an emergency situation.

The team are now finding out about the circumstances that most commonly led to a general anaesthetic being performed after a regional anaesthetic had failed. 

What difference will this project make?

The findings from this project will help healthcare teams make better decisions about the most appropriate type of anaesthesia to use for each mother having a caesarean section. This will help to reduce the risks of surgery for both mother and baby, particularly in emergency situations.

Get our research updates

Tommy's funds research across the UK investigating the reasons for pregnancy complications and loss. If you're interested in being kept updated about our research and news from Tommy's, click here.