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Surgical Intervention, Anaesthesia, and Breastfeeding: Drug Compatibility of Anaesthetics and Analgesics

anaesthesia and breastfeeding


1. Introduction

The benefits of breastfeeding, both for maternal and infant health, are well established and documented, notably in the series published by The Lancet in 2016.

The World Health Organisation recommends exclusive breastfeeding for the first six months of life, followed by continued breastfeeding alongside solid foods until at least two years of age.

In France, breastfeeding rates remain modest. According to the Epifane 2021 study, the initiation rate of breastfeeding in maternity units was 77%. The median duration of breastfeeding was 20 weeks, and at 6 months of age, one third of infants were still being breastfed.

Recommendations regarding the use of medications during breastfeeding remain insufficiently known to the general public. Many mothers still rely on medication package inserts, which frequently leads to interruption ,sometimes unjustified, of breastfeeding. The Epiphane study reports that 7% of mothers introduce formula milk or wean their infant due to medication use.

In France, the CRAT website constitutes a primary reference for healthcare professionals regarding the transfer of medications into breast milk. Other international resources are also available, including LactMed, Hale's textbook, and e-lactancia.

In the context of surgical anaesthesia, American (2024) and British (2020, updated in 2026) recommendations have been published, yet they remain poorly disseminated among healthcare professionals.

De Hondt et al. published in 2026 a study of 193 participants who had undergone surgical intervention while breastfeeding: among them, 24% were advised to breastfeed immediately, 5.7% were instructed to pump and discard milk once, 19.2% were instructed to pump and discard for 12 hours, and 16.1% for 24 hours. Mothers did not necessarily follow these instructions and sought information on forums or websites. The authors conclude on the importance of educating healthcare professionals on this topic.

Lactation consultants are therefore on the front line, reporting that breastfeeding mothers ask them how to proceed during surgical intervention, and in particular about the possible need to pump and discard their milk for a given period.

We present here a review of the transfer into breast milk of the main drugs used in anaesthesia in breastfeeding mothers, along with a reminder of the practical precautions to take during surgical intervention.


2. Anaesthesia and Breastfeeding: Pharmacological Basis of Drug Transfer into Breast Milk

The compatibility of a drug with breastfeeding rests on the evaluation of several pharmacokinetic and pharmacodynamic parameters. These factors influence the quantity of active substance that passes into breast milk and its capacity to be absorbed by the infant (Hale & Rowe, Medications and Mothers' Milk, 2023).

  • Plasma half-life of the drug: The half-life determines how long the drug remains in the maternal circulation. The longer it is, the higher the plasma concentration remains, potentially increasing transfer into breast milk. Molecules with a short half-life generally result in lower or transient passage into milk. The half-life is therefore a key factor in planning medication intake in breastfeeding mothers (Hale 2023).

  • Oral bioavailability in the infant: Even when a drug passes into milk, it must still be absorbed by the infant's gastrointestinal tract to produce a systemic effect. Molecules with low oral bioavailability present very low risk despite measurable passage into milk.

  • Administered dose and frequency of administration: A high maternal dose, or repeated administrations, increase plasma concentration and therefore the potential for transfer into milk.

  • Lipophilicity: Lipophilic drugs cross cell membranes more easily and accumulate more in a lipid-rich compartment such as breast milk. This may increase the milk concentration, particularly in mature milk which is more lipid-rich. Lipophilic anaesthetics and analgesics often show measurable but transient passage.

  • Molecular weight: Molecular weight influences a molecule's ability to cross the intercellular junctions of lactocytes. Small molecules (< 300 Da) cross more easily than large ones (> 800 Da).

  • Protein binding: Drugs highly bound to maternal plasma proteins (often > 90%) have limited passage into milk, as only the free fraction diffuses into milk. High protein binding is generally protective, reducing the amount available for transfer.

  • Mode of transfer into breast milk — passive diffusion and concentration gradient: Most drugs cross the lactocyte membrane by passive diffusion. The pH of milk (approximately 7.0 versus 7.4 in plasma) may also favour 'ion trapping': basic molecules become more ionised in milk and may be slightly retained there (Hale & Rowe 2023; Anderson 2016).

Assessment is usually based on the Relative Infant Dose (RID), which compares the dose received through breast milk per unit body weight of the infant to the maternal dose. An RID < 10% is generally considered compatible with breastfeeding (Hale 2023).


3. International Recommendations

To date, there are no professional practice guidelines for the use of anaesthetics in breastfeeding mothers in France. Anaesthesiologists therefore rely on the precautionary principle when advising mothers to avoid breastfeeding for a given period after anaesthesia for surgical intervention.

American and British expert recommendations indicate that it is not necessary to pump and discard milk for any given period after surgical intervention, and that breastfeeding may resume as soon as the mother is awake and alert.


4. Details of Drug Transfer into Breast Milk and Drug Compatibility

We provide information on the main drug classes used for anaesthetic management in surgical intervention and their compatibility with breastfeeding.


a. Anaesthetics

Intravenous anaesthetics

Most intravenous anaesthetic agents have low oral bioavailability and a short half-life; they are therefore compatible with use during surgical intervention in breastfeeding women.

  • Propofol (RID 4.44%), thiopental (RID: 1.77–5.94%), and etomidate (RID: 0.81%–3.97%): the quantities that pass into breast milk are low, and breastfeeding may resume as soon as the mother has sufficiently recovered from general anaesthesia to breastfeed (Hale).

  • Ketamine: ketamine and its active metabolite appear in breast milk at very low concentrations, and its oral bioavailability is low, implying low risk for breastfed infants. Available data indicate that the use of ketamine in breastfeeding mothers has no effect on the breastfed infant or on lactation. Until more data are available, ketamine should be used with careful monitoring of the infant for signs of sedation, poor feeding, and inadequate weight gain.

Inhalational anaesthetics (sevoflurane, isoflurane, desflurane, nitrous oxide, and halothane)

These agents are largely eliminated after anaesthesia through exhalation; they have a short half-life and rapid elimination. Their use during anaesthesia is compatible with breastfeeding.


3.2. Sedation

Benzodiazepines: short half-life benzodiazepines are recommended, particularly for mothers of newborns and premature infants.

  • Midazolam (RID: 0.63%): a short half-life molecule, generally given as a single dose. Very low passage into breast milk, therefore compatible with breastfeeding.

  • Diazepam (RID: 0.88–7.14%): should be used with caution as its active metabolite has a long half-life and passage into breast milk occurs at significant doses. However, single-dose use is compatible with breastfeeding.

  • Dexmedetomidine: negligible passage into breast milk due to a large volume of distribution, high plasma protein binding, and a short elimination half-life. Breastfeeding may resume as soon as the mother has sufficiently recovered from general anaesthesia to breastfeed.


3.3. Analgesics


  • Paracetamol (RID: 6.41–24.23%): the dose passing into breast milk is below the paediatric dose; compatible with breastfeeding.

  • Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

Ibuprofen (RID: 0.1–0.7%), diclofenac, naproxen, celecoxib, ketorolac, parecoxib: are compatible with breastfeeding. Ibuprofen, ketoprofen, flurbiprofen, or diclofenac should be preferred (Hale).

Aspirin: excreted in breast milk at doses dependent on the maternal dose. Low-dose aspirin for its antiplatelet action may be used in breastfeeding women (CRAT, LactMed), but should not be used at analgesic or repeated doses (CRAT). The risk of Reye's syndrome in the infant following ingestion of breast milk containing aspirin is unknown (LactMed) but considered unlikely (e-lactancia).

  • Nefopam (RID 2.6%)

Nefopam is a non-opioid analgesic used for moderate to severe pain, notably in cases of caesarean section or episiotomy. It can be used intravenously or orally. It is excreted in milk in clinically non-significant quantities and is compatible with breastfeeding (e-lactancia).

The CRAT website indicates that in the 48 hours after delivery, quantities found in breast milk are low, and that due to a lack of data beyond 48 hours, it is preferable to pump and discard milk during nefopam use (CRAT). Breastfeeding may resume 8 hours after the last dose of nefopam.

The 2026 British recommendations indicate that nefopam is a non-opioid analgesic with a half-life of 3 to 8 hours, plasma protein binding of 71–76%, and a relative infant dose of 2.6%. Breastfed infants should be monitored for sedation and diuresis.

  • Opioids

Morphine (RID: 9.09–35%) passes into breast milk in small quantities but its use is possible with breastfeeding. With repeated use, monitoring of the infant (sedation and respiratory depression) is recommended.

The CRAT mentions that in post-caesarean analgesia, during 24 to 72 hours after delivery (intravenous then oral), the newborn receives up to 2% of the oral neonatal dose of morphine and that no adverse effects have been reported in approximately twenty infants breastfed by mothers receiving morphine. Beyond this period, there are few data on morphine during breastfeeding.

As with nefopam, beyond 48 hours, the CRAT indicates that it is preferable to suspend breastfeeding during morphine treatment. Breastfeeding may resume approximately 4 hours after the last dose of morphine.

Long-term opioids (fentanyl, oxycodone, hydromorphone) are contraindicated during breastfeeding. If a level 3 analgesic is necessary in a breastfeeding woman, a single dose of morphine may be considered, but prolonged treatment is not compatible with continued breastfeeding (HAS).

  • Oxycodone (RID: 1.01–8%): passes into breast milk (10% of the maternal dose) and is metabolised to oxymorphone (active metabolite) via cytochrome P450. Multiple cases of sedation and respiratory difficulties in newborns have been reported in the literature. Depending on the metabolism (if the mother is an ultra-rapid metaboliser), there is a risk of accumulation in the infant and respiratory depression.

  • Hydromorphone (RID: 0.67%): hydromorphone is one of the active metabolites of oxycodone and is excreted in small quantities into breast milk. One case of adverse effects in an infant (respiratory depression treated with naloxone) has been reported; it is therefore recommended to use it with caution, at minimal dose for 2–3 days with infant monitoring. The British recommendations indicate that it is a potent narcotic analgesic for which breastfeeding data are limited.

  • Codeine (RID: 0.6–8.1%) and dihydrocodeine are opioids metabolised via the cytochrome P450 CYP2D6 to an active morphine metabolite. There is genetic polymorphism for this cytochrome, with some individuals metabolising more rapidly, potentially leading to higher concentrations of active metabolites in breast milk. The use of these drugs should therefore be limited during breastfeeding. See our article on the subject of codeine!

  • Tramadol (RID: 2.86%): transfer of tramadol and its active metabolite into milk is low; it is therefore compatible with breastfeeding.

  • Pethidine: pethidine is excreted in milk in small quantities, and difficulties in establishing breastfeeding have been observed in infants whose mothers received pethidine rather than morphine. However, in single dose, breastfeeding is compatible.

  • Remifentanil: its very short half-life makes passage into breast milk unlikely. Furthermore, oral bioavailability is low. Breastfeeding may resume as soon as the mother has sufficiently recovered from general anaesthesia to breastfeed.

  • Fentanyl (RID: 2.9–5%) / alfentanil: oral bioavailability is low, and excretion into milk is in non-significant quantities; their use is therefore compatible with breastfeeding.

  • Sufentanil: used epidurally or intravenously during labour or after birth, the quantities ingested by the newborn via breast milk are minimal and breastfeeding is compatible (LactMed, e-lactancia).


3.4. Local Anaesthetics

The Academy of Breastfeeding Medicine protocol states: "Local anaesthetics such as lidocaine, bupivacaine, and ropivacaine can be used safely in breastfeeding mothers. These local anaesthetics, along with others, are poorly absorbed orally and their large polarised molecules do not easily pass into breast milk." The 2026 British recommendations also indicate the possibility of breastfeeding when these molecules are used.


3.5. Neuromuscular Blocking Agents

  • Non-depolarising muscle relaxants (e.g. mivacurium): they have low lipid solubility and low oral bioavailability, and a high molecular weight (mivacurium: 1100 Da). They are ionised at physiological pH and will not be present in significant quantities in milk. Breastfeeding is possible once neuromuscular block anaesthesia is complete.

  • Suxamethonium: its elimination half-life of less than one minute makes passage into milk unlikely, and its low oral bioavailability would not allow passage into the infant's plasma. Breastfeeding is possible once neuromuscular block anaesthesia is complete.


3.6. Drugs Reversing the Effect of Neuromuscular Blocking Agents

  • Neostigmine: not excreted into breast milk. Breastfeeding is possible.

  • Sugammadex: its high molecular weight makes passage into breast milk unlikely, and its low oral bioavailability makes passage into the infant's plasma unlikely. Breastfeeding is compatible.


3.7. Antibiotics

Antibiotics used in surgical antibiotic prophylaxis are generally compatible with breastfeeding


3.8. Antiemetics

The Academy of Breastfeeding Medicine states: "Antiemetics are commonly used during the perioperative period and most of these drugs are considered safe during breastfeeding. Ondansetron, dexamethasone, and metoclopramide may be preferred due to their absence of sedative effects. Prochlorperazine, promethazine, and scopolamine are probably safe, but may cause maternal sedation; promethazine and scopolamine may also have a negative effect on milk supply if administered repeatedly."

The 2026 British recommendations note that domperidone and metoclopramide, being galactagogues, increase milk secretion and should be avoided in cases of recent weaning (for example in cases of breast cancer).


5. Practical Considerations Regarding Anaesthesia for Surgical Intervention and Breastfeeding


The British and American recommendations outline the following data:

Before the procedure

  • Inform the anaesthesiologist that you are breastfeeding before the procedure.

  • Breastfeed or pump breast milk before the procedure to ensure an adequate supply for the infant while the mother is in theatre.

  • Consider pumping and storing milk before the procedure in case breastfeeding is delayed.

During the procedure

  • Prefer anaesthetic agents with the lowest transfer into breast milk and the shortest half-lives.

  • Prefer regional anaesthesia whenever possible, as it minimises systemic exposure.

  • Use multimodal analgesia (paracetamol, NSAIDs, local anaesthetics, etc.) to reduce opioid requirements.

After the procedure

  • Breastfeeding may resume as soon as the mother is awake, alert, and capable of holding the infant safely.

  • Pumping and discarding milk is not routinely necessary after a surgical procedure under general anaesthesia.

  • Monitor the infant for unusual drowsiness, particularly in newborns and premature infants, especially after long procedures or when opioid analgesics are used.




References

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