Why do I need to see an anaesthetist during my pregnancy?

Information for pregnant women with a high body mass index (BMI)

One of the aims of care during pregnancy is to identify those women who may need extra help with delivering their baby. One thing that makes this more likely is a high body mass index – BMI. (Body mass index is a relationship between your height and your weight, and is a way of working out how overweight you are.) For example, if your BMI is above 35, you are twice as likely to need a Caesarean section (and need an anaesthetic) compared to women whose BMI lies within the normal range of 20 to 25 (the scientific paper containing this research is listed at the end of this leaflet).

In most cases it is better for you to have a regional anaesthetic (a spinal or an epidural) for a Caesarean section. This means the injection is given into your back (either by injection into the spine or through a tube placed into your back) to make the lower part of the body numb.With a regional anaesthetic you stay awake during the operation. Being awake has many advantages for you and your baby during and after the operation. There are times when we need to deliver a baby as quickly as possible. If you have an epidural during labour that is working well, we can often use it for either a caesarean section or if we need to deliver your baby using special equipment, for example forceps or ventouse (a suction cup).

If you have a high BMI, this can make anaesthetic procedures more difficult. It may be harder to find the correct place to put the needle in to give the anaesthetic and be more difficult to get the anaesthetic to work properly straight away. A high BMI may also cause problems with general anaesthesia during and after the operation (if you have a general anaesthetic, you will be asleep during the operation).

During your pregnancy you may be offered an appointment to talk to an anaesthetist. This will allow us to see and examine you before the date you are due to give birth. We can discuss and plan pain relief and anaesthetic choices with you for your labour and delivery. It is easier to do this in relaxed surroundings, rather than trying to explain things when you are having labour pains. Things can happen very quickly during labour and the more information you have, the more prepared you will be.

After this discussion the anaesthetist will suggest one of the following plans for pain relief in labour.

  • If labour is not straightforward, you should think about having an epidural early during labour rather than later because it might take longer than usual to give you a spinal or epidural anaesthetic.
  • The anaesthetist may encourage you to have an epidural in labour so that you can avoid a general anaesthetic if you need a Caesarean section.

When you are admitted to the labour ward please tell the midwives that you have seen an anaesthetist. This will allow the anaesthetist on duty to go over the plan suggested by the senior anaesthetist who saw you during your pregnancy.

We will give you an antacid tablet (such as ranitidine) throughout labour. This reduces the acidity in your stomach. It is also best not to eat any solid or fatty food when you are in labour. It is safer to drink just water or non-fizzy sports drinks (such as Lucozade Sport™).

After you have had your baby we might need to give you heparin injections for a few days. This thins the blood and is to try to prevent blood clots forming in your legs or chest. This problem is more common during and after pregnancy and is even more likely in women with a highBMI. We will give you heparin once or twice a day.


Maternal obesity, length of gestation, risk of post-dates pregnancy and spontaneous onset of labour at term.British Journal of Obstetrics & Gynaecology: An International Journal of Obstetrics & Gynaecology. Volume 115, Issue 6, Date: May 2008, Pages: 720 to 725.FC Denison, J Price, C Graham, S Wild, WA Liston.


If your BMI is above 35, you are more likely to need some sort of help with the delivery of your baby than someone with a lower BMI.

  • It is generally better to stay awake while your baby is delivered.
  • Giving you a general anaesthetic may be more difficult than for women with a lower BMI, and the anaesthetists need to plan for that.
  • It can be more difficult and take longer to do epidurals and spinals. It may be better to have an epidural early in labour rather than later, in case you need a Caesarean section or we need to deliver your baby quickly using forceps or ventouse.
  • When you go onto the labour ward to have your baby, tell the midwives that you need to see the anaesthetist on duty.
  • When you are in labour it is best not to eat any solid or fatty foods.

This booklet was written by the obstetric anaesthetists at the Royal Berkshire Hospital.It has been edited by the Information for Mothers Subcommittee of the Obstetric Anaesthetists’ Association.

The subcommittee was made up of the following people.

  • Dr Rosie Jones (chairman)
  • Charis Beynon (National Childbirth Trust representative)
  • Shaheen Chaudry (consumer representative)
  • Dr Rachel Collis
  • Dr Rhona Hughes (Royal College of Obstetricians and Gynaecologists representative)
  • Gail Johnson (Royal College of Midwives representative)
  • Dr Michael Kinsella
  • Dr Ratnasabapathy Sashidharan

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