What are the risks to a 2-year-old child if their mother takes Mifegymiso (mifepristone) while breastfeeding?

Mifegymiso (Mifepristone) Safety During Breastfeeding for a 2-Year-Old Child

Mifepristone should be avoided while breastfeeding a 2-year-old child due to potential exposure through breast milk, with limited safety data available. 1

Mifepristone Transfer into Breast Milk

• Mifepristone is present in human milk, though there are limited data on the specific amount transferred or effects on breastfed children 1
• The FDA drug label indicates that after a single 600mg dose, a small amount of mifepristone was detected in breast milk with an estimated relative infant dose of 0.5% 1
• The half-life of mifepristone is longer with repeat dosing compared to a single dose, which may result in greater exposure with long-term use 1

Risk Assessment for Breastfeeding a 2-Year-Old

• For mothers taking mifepristone while breastfeeding, the FDA recommends considering pumping and discarding milk during treatment and for 18-21 days (5-6 half-lives) after the last dose before resuming breastfeeding 1
• While most medications taken by breastfeeding mothers are compatible with breastfeeding, mifepristone has insufficient safety data to recommend its use during breastfeeding 2
• Risk assessment for medication use during breastfeeding should consider:
  • The potential risk to the breastfed child
  • The benefits of breastfeeding
  • The risks of untreated maternal condition 3

Factors Affecting Drug Transfer to Breast Milk

• Drug transfer into breast milk depends on several factors:
  • Molecular weight of the drug
  • Plasma protein binding
  • Lipid solubility
  • pH of the drug relative to milk 2
• The relative infant dose (infant dose mg/kg/day divided by maternal dose mg/kg/day) is considered a valuable guide to medication safety during breastfeeding; a value <10% is generally considered safe 2

Considerations for Breastfeeding a Toddler

• By age 2, breast milk is no longer the primary source of nutrition for the child, which may reduce overall exposure risk compared to exclusively breastfed infants 2
• However, the potential for drug accumulation in a breastfed child must still be considered, especially with medications that have limited safety data 3
• The developmental and health benefits of breastfeeding should be weighed against potential adverse effects from mifepristone exposure 1

Recommendations

• If mifepristone treatment is necessary, temporary interruption of breastfeeding is recommended during treatment and for 18-21 days (5-6 half-lives) after the last dose 1
• During this period, mothers can pump and discard milk to maintain lactation if they wish to resume breastfeeding later 1
• If a breastfeeding child shows any unusual symptoms or changes in feeding patterns while the mother is taking medication, this should be promptly evaluated 4
• For medication safety information during breastfeeding, consult specialized resources such as LactMed (published by the National Library of Medicine) 2

Monitoring and Follow-up

• If breastfeeding must continue while the mother takes mifepristone (not recommended), careful monitoring of the child for any adverse effects is essential 5
• Any unexplained illness or failure to thrive in a breastfed child should prompt consideration of maternal medication exposure as a potential cause 6
• In cases where medication exposure through breast milk is suspected as causing symptoms, collection of maternal plasma, breast milk, and infant plasma samples for drug assay may be considered 6