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

Opinions can vary slightly on the shortest safe fasting time for a breastfed baby. Currently most organisations recommend fasting for four hours after an infant has had breast milk. In the United Kingdom, The Royal College of Anaesthetists (RCoA), Association of Anaesthetists of Great Britain and Ireland (AAGBI) and Association of Paediatric Anaesthetists of Great Britain and Ireland (APAGBI) have produced a guide which states:

Children are much more comfortable if they don’t have to wait longer than necessary without food and drink.
The following are commonly agreed timings for when you can give your child something to eat or drink before non-urgent surgery, but please follow the hospital’s instructions given to you, as they may be different.

  • Children can have a light meal and/or a glass of milk six hours before surgery. After that they must not eat anything including sweets and should avoid chewing gum.
  • Breastfed babies can have breast milk up to four hours before their surgery.
  • Bottle-fed babies can have formula milk up to six hours before surgery (please check with your hospital for any different instructions for very small or premature babies).
  • Children should continue to drink water or very dilute squash until one hour before their surgery. This helps them to stay well hydrated and comfortable.

What do others say?

American based organisations the Academy of Breastfeeding Medicine (ABM), and the American Society of Anesthesiologists (ASA) also 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 4 January 2022] 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.

American Society of Anesthesiologists

In Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration, ASA, 2017 [accessed 4 January 2022] 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.

Is a fasting interval less than four hours ever recommended?

A paper by Cook-Sather and Litman (2006) discussed whether shorter fasting periods for breast milk (three hours), formula (four hours) and light meals (six hours) may be possible:

…the relative safety and benefits of allowing clear liquids up to 2 hr prior to anesthesia for otherwise healthy children are well established. Shortened fasting periods for breast milk (3 hr), formula (4 hr) and light meals (6 hr) are supported by accumulated experience and an evolving literature that includes evidence of minimal gastric fluid volumes (GFVs) at the time of surgery. Ideal fasting intervals for children with disorders that may affect gastrointestinal transit have yet to be determined.

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

For infants under six months of age having an elective procedure, formula may be given up to four hours, breast milk up to three hours and clear fluids (no more than 3ml/kg/hr) up to one hour prior to anaesthesia.

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.
Baby asleep in sling on father's chest
A sling may help to settle a baby to sleep during the fasting period

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.


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