Fasting For Surgery

Why fast before surgery?

Fasting for surgery refers to not eating or drinking for several hours before having a general anaesthetic for a surgical procedure. The reason for fasting before surgery is so that the stomach is empty. An empty stomach reduces the risk of any stomach contents entering the lungs (pulmonary aspiration) while patients are relaxed and sleepy due to the anaesthetic.

While an adult or older child will understand why they must not eat or drink for a certain number of hours, a breastfed baby or toddler doesn’t have this understanding. A breastfed infant can’t understand why he can’t feed on demand, even if he isn’t especially hungry or thirsty— because he breastfeeds for many other reasons such as for comfort or to fall asleep. Expecting a breastfed baby not to breastfeed for enforced periods of time can be very stressful to mother and baby. This article looks at the recommendations for the minimum fasting time so that stress and upset can be reduced.

Breast milk is digested quickly

Breast milk is digested much more quickly than formula or solid food which means breastfed babies have shorter fasting guidelines than formula fed babies.¹

Guidelines for a baby fasting for surgery

In 2022; Pre-operative fasting in children A guideline from the European Society of Anaesthesiology and Intensive Care provided new recommendations for children fasting for surgery. Alyson Walker, Consultant Paediatric Anaesthetist for NHS Greater Glasgow and Clyde Paediatrics summarises:

Children should be fasted for the minimum time possible.  Although traditional guidance recommended 6 hours for solids, 4 hours for breast milk and 2 hours for clear fluids, recent evidence has shown that drinking clear fluids until 1 hour before surgery does not increase the risk of aspiration. Breast milk fasting times have been reduced to 3 hours, and all other milk can be consumed up until 4 hours pre-operatively.

United Kingdom

In the United Kingdom, The Royal College of Anaesthetists (RCoA), Association of Anaesthetists and Association of Paediatric Anaesthetists of Great Britain and Ireland (APAGBI) have produced a joint guide which states:

Babies are usually allowed to have breast milk until three hours before surgery, but you should follow any instructions provided by the hospital.

Australian and New Zealand

The Australian and New Zealand College of Anaesthetists (ANZCA) say:

4.2.2.1 For infants up to 12 months of age:
• breast milk feeding should be encouraged until 3 hours
• formula and non-human milk may be encouraged until 4 hours *
4.2.2.2 For children older than 12 months of age:
• breast milk feeding should be encouraged until 3 hours
• formula and non-human milk should be regarded as similar to solids with a fasting time of 6 hours
* 200ml or 20ml/kg for formula and cow’s milk, whichever is smaller

United States of America

American based organisations the Academy of Breastfeeding Medicine (ABM), and the American Society of Anesthesiologists (ASA) still recommend four hours as the fasting interval before surgery when breast milk is being consumed.

The Academy of Breastfeeding Medicine

In their Clinical Protocol #25: Recommendations for Preprocedural Fasting for the Breastfed Infant: ‘‘NPO’’ Guidelines, 2012 [accessed 9 September 2025] the ABM recognises that it can be stressful for a breastfed infant to fast for any length of time, and states that a fasting period of longer than four hours can be harmful for infants. Their recommendations include:

• Do not breastfeed or give breast milk in the four hours before having an anaesthetic
• Do not allow non nutritive suckling at an empty breast within four hours of anaesthesia due to the risk of breast milk in the tummy prior to surgery.
• Clear fluids such as water can be given until two hours before the infant has an anaesthetic.
• Postopone surgery if the guideline of four hours without breast milk or two hours without clear fluids have not been met—unless the procedure is an emergency.

In Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration, ASA, 2017 [accessed 9 September 2025] the ASA states that breastfed babies should fast (not have any breast milk) for four hours before having an anaesthetic. Clear fluids can be ingested up to two hours before a procedure requiring an anaesthetic. Breastfeeding does not seem to be mentioned in a 2023 update.

Paediatricians Lawrence and Lawrence ² discuss limiting breastfeeding from four hours prior to surgery but allowing feeding from a pre-pumped and empty breast for comfort—up to two hours before surgery. However, feeding from an empty breast is not recommended by the Academy of Breastfeeding Medicine (ABM, 2012). The decision on the safest and most appropriate fasting time for your baby will need to be discussed with your baby’s surgeon and anaesthetist.

Not breastfeeding can be stressful for baby

During a fasting period a breastfed baby may cry due to separation anxiety and hunger. The Academy of Breastfeeding Medicine Protocol #25 explains that it is important to keep a baby calm before surgery. Extensive crying could lower their oxygen levels or slow down their digestion (stomach emptying). In order to reduce a baby’s anxiety, options include:

• Try non-nutritive sucking with a pacifier as a temporary comfort measure to reduce crying (ABM, 2012)
• Going for a drive in a car or carrying a baby in a sling can settle some babies to sleep
• It may be helpful if someone other than the breastfeeding mother tries to comfort the baby so that they don’t expect to breastfeed
• The timing of surgery can make a difference: later in the day may make distraction easier than if the fasting period is through the night.

Stay comfortable

During the fasting period a breastfeeding mother may need to remember to express her milk by pumping or hand expression to stay comfortable and avoid engorgement or mastitis at an already very stressful time.

After surgery

Unless your health professionals have any concerns, breastfeeding can continue as soon as your baby is ready to feed by mouth (ABM, 2012; Lawrence & Lawrence, 2016; Wambach and Spencer, 2020 p 627).

After a minor procedure under anesthesia, if her child is stable, otherwise healthy, and the type of surgery does not prevent oral intake, a mother can immediately begin to breastfeed her infant as soon as he or she is awake. This increases comfort, reduces pain in the child, and is widely practiced and evidence-based, even following cleft lip and palate repairs.

Summary

Breast milk is digested more quickly than formula which allows for shorter recommended fasting times for the breastfed baby prior to having an anaesthetic. Newer guidelines recommend the fasting period for breast milk should be three hours. Discuss the safest fasting time for your baby with your baby’s health professionals.