Body Mass Index (BMI) and Childbirth
Risks:
One of the aims of care during pregnancy is to identify women who may need extra help
during the birth of their baby. One factor that increases the risk of problems during birth is
being overweight. Women with a BMI of 45 and above will be referred to anaesthetist.
BMI is the relationship between your height and weight. Women who are very overweight
have a BMI higher than 35. These women are slightly more likely to need a caesarean section to deliver their baby.
This means that women with a high BMI are more likely to need an anaesthetic to allow a
caesarean section to be carried out. A high BMI can also make some procedures more difficult and time consuming, such as putting a drip into a vein.
It is usually best for you to remain awake during the birth of your baby by choosing to have a spinal or epidural anaesthetic for your caesarean section. A high BMI can make general anaesthesia more difficult. For example, when asleep it may be harder to put a breathing tube into your throat.
Benefits:
Being awake for a caesarean section has many advantages to you and your baby, both during and after the operation. Pain relief drugs given with a spinal or epidural are more effective so that the amount of pain felt afterwards is often much less than after having a general anaesthetic.
However, it can be more difficult to find the right place in the back to put a needle for spinal or epidural injection, and therefore it may take longer.
More information about having an epidural, spinal or general anaesthetic, including the risks, is given in our separate leaflets. Please ask if you have not been given a copy of these.
During pregnancy an appointment to meet an anaesthetist may be offered. This will allow an anaesthetist to meet you and make an assessment, and discuss pain relief and anaesthetic choices for the labour and birth. This is better done in relaxed surroundings during pregnancy, rather than when in labour.
After meeting with the anaesthetist some recommendations about pain relief in labour may be made. For example, the anaesthetist may suggest to you that, if labour is not straightforward, having an epidural earlier rather than later may be needed, because putting an epidural in may take longer than usual.
When arriving on delivery suite please tell the midwives if an anaesthetic assessment has been done. The anaesthetist on duty will review the plan suggested by the senior anaesthetist during pregnancy. If an anaesthetist has not made a plan during pregnancy, the duty anaesthetist will make one.
Omeprazole tablets will be given to you during labour. This is a drug that helps to reduce the acidity in the stomach, and will make it safer if an urgent anaesthetic to deliver the baby is needed.
Soon after the birth of your baby heparin injections may be given for a few days and compression stockings may need to be worn.
These help prevent blood clots in the legs or lungs, which are more common during and after pregnancy, and even more likely in women with raised BMI. We will discuss this after the baby is born.
To summarise:
• If your BMI is above 35, it is more likely that some form of help with the birth of the baby is needed, than someone with a lower BMI.
• It is generally better to stay awake during a caesarean section birth.
• General anaesthesia may be more difficult and time consuming and the anaesthetists need to plan for this.
• It can be more difficult to site epidurals and spinals.
• When admitted to delivery suite to have your baby, the anaesthetist on duty may see you.
For further information about the details in this leaflet please speak to your midwife.
Pain Relief in Labour (OAA publication)
Caesarean Section: your choice of
anaesthesia (OAA publication)
References
Saving Mothers Lives (CEMACH). London;
RCOG Press; 2007 [www.cemach.org.uk]
