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Breastfeeding is recommended by the World Health Organization as the best source of nutrition for infants, with potential health benefits for both mother and child. Anesthesiologists are frequently asked about the safety of medications in breastfeeding infants and time from anesthesia and surgery to resuming breastfeeding.

Transfer of medications from the maternal system to breastmilk depends upon protein binding, lipid solubility, molecular weight, pKa, and maternal plasma levels of the drug. Medications that are highly lipid soluble, less protein bound, low molecular weight, and a higher pKa will have a higher rate of transfer to breastmilk. Passage is largely via passive diffusion as very few drugs are actively transported into breastmilk.

Most medications can cross into colostrum (immediately after delivery) because the intracellular junctions between lactocytes close by 48 to 72 hours postpartum. However, because colostrum volume is low and neonate intake is also low, risk of potentially “harmful” breastmilk to the infant starts after day 3 of life.

The RID (%) (Relative Infant Dose)

RID=estimated daily infant dose via breastmilk (mg/kg/day)infant therapeutic dose (mg/kg/day)×100

RID levels less than 10% are generally considered safe. Fortunately, almost all anesthetics and drugs used in delivering a multimodal anesthetic have RIDs significantly less than 10%. A few drugs not recommended for breastfeeding mothers include codeine, tramadol, amphetamines, chemotherapy agents, ergotamine, and statins.

Narcotics are the most concerning, but improved pain translates to better breastfeeding outcomes in the postpartum period. Narcotics used for procedural anesthesia and post-surgical pain relief in breastfeeding mothers can be administered safely within reason. There are very few rigorous studies regarding procedural sedation and anesthesia in breastfeeding mothers, and information guiding recommendations is gathered from small sample observations, case studies, and animal studies which may not translate to humans; thus guidelines are based upon expert opinion or GRADE III and IV quality of evidence (poor).


Clinical Practice and Guidelines for Anesthesiologists1-5

Multimodal pain regiment is a pharmacologic method which combines various medications at their lowest appropriate doses for effective pain relief, including local anesthetics, opioids, acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), and alpha-2 agonists.

  • Drugs with high protein binding, low RID, and shorter half-life are preferred.

  • Commonly available medications in the perioperative period (midazolam, fentanyl, propofol, inhalational anesthetics, and antiemetics) are considered safe, especially when single doses are used, and when an infant is healthy and term.

  • Resume breastfeeding when the breastfeeding mother is awake and alert following anesthesia. (Resumption of maternal mentation is an indication that medications have redistributed from the plasma and entered adipose where they are more slowly released.)

  • If there is concern by the caregiver and/or breastfeeding mother about transfer of medications to breastmilk, the mother ...

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