Raised BMI and your options for labour pain relief

One of the aims of antenatal care is to identify those women who may need extra support during pregnancy and birth. One thing that makes this more likely is if you have a high body mass index or BMI.

BMI (body mass index) is a calculation that uses your height and weight to estimate whether you are a healthy weight for your height. You can use the NHS website to calculate your BMI.

If you have a raised BMI, it's natural to wonder whether this will affect your labour or birth. The reassuring news is that most women with a raised BMI have a healthy pregnancy and give birth safely.

But a higher BMI can increase the chance of some pregnancy and birth complications, such as caesarean birth. Because of this, your maternity team may recommend some additional appointments or monitoring to help keep you and your baby safe.

Why might I need to see an anaesthetist?

Some hospitals offer an antenatal appointment with an anaesthetist if your BMI is above a certain level.

This appointment isn't because anyone expects something to go wrong. Instead, it allows you to discuss your options for labour pain relief.

You can also ask questions about epidurals and spinal anaesthesia and talk about anaesthesia if a caesarean birth becomes necessary.

It’s a good opportunity to plan ahead, so that your care is as safe and straightforward as possible.

Does a raised BMI affect my choices for pain relief during labour?

No. You can usually choose from the same pain relief options as anyone else in labour. It's worth noting that some procedures, such as epidurals, can take longer to site if you have a raised BMI.

This includes movement and water immersion (where appropriate), TENS, gas and air (Entonox), opioid medicines, remifentanil patient-controlled analgesia (PCA) (where available) and epidural analgesia.

The best option depends on your individual circumstances and preferences.

Why is an epidural often recommended earlier with a higher BMI?

If you think you might want an epidural, your anaesthetist or midwife may recommend requesting it earlier rather than waiting until labour is very advanced.

This is because placing an epidural can sometimes take longer in women with a higher BMI.

Having it working well before an emergency arises can provide excellent pain relief during labour. If an emergency caesarean birth becomes necessary, it can often be used instead of giving a general anaesthetic.

This doesn't mean you have to have an epidural. It simply means that, if you choose one, earlier placement may be safer and less stressful.

Why can epidurals sometimes be more difficult?

With a raised BMI, it may be harder to feel the bony landmarks in your back; the epidural needle has to travel further; and positioning can be more challenging.

Experienced obstetric anaesthetists perform epidurals for women with a raised BMI every day, and extra equipment, such as ultrasound, may occasionally be used to help.

What if I need a caesarean birth?

Most caesarean births are performed using spinal or epidural anaesthesia, allowing you to stay awake for the birth of your baby.

However, a raised BMI increases the risks associated with a general anaesthetic, which can make it more difficult to manage the airway and breathing.

This is one reason why anaesthetists often encourage women who may need a caesarean birth to consider having a well-functioning epidural in labour.

Other things you may notice during labour

Your team may recommend placing a cannula early in labour, additional monitoring of you or your baby, and giving birth in a consultant-led maternity unit where specialist support is immediately available.

These recommendations are made to improve safety rather than because a problem is expected.

Questions you may wish to ask your anaesthetist

Would you recommend an epidural in my situation?
If I want an epidural, when would be the best time to request one?
If I needed a caesarean birth, what type of anaesthetic would be most likely?
Is there anything I can do before labour to make an epidural easier?
Does my BMI affect where I should give birth?

Remember

Having a raised BMI does not mean that you cannot have the birth you hope for.

Your maternity and anaesthetic teams are there to help you make informed choices, provide effective pain relief and keep both you and your baby as safe as possible.

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