Caffeine appears in breastmilk rapidly after maternal ingestion. Insufficient high-quality data are available to make good evidence-based recommendations on safe maternal caffeine consumption.[1] Fussiness, jitteriness and poor sleep patterns have been reported in the infants of mothers with very high caffeine intakes equivalent to about 10 or more cups of coffee daily. Studies in mothers taking 5 cups of coffee daily found no stimulation in breastfed infants 3 weeks of age and older. A maternal intake limit of 300 to 500 mg daily might be a safe level of intake for most mothers, although European authorities set a likely safe level at 200 mg.[2-4] Maternal doses of caffeine greater than 130 mg daily may decrease weight gain in their exclusively breastfed infants, but this needs further confirmation.[5] However, preterm and younger newborn infants metabolize caffeine very slowly and may have serum levels of caffeine and other active caffeine metabolites similar to their mothers' levels, so a lower intake level preferable in the mothers of these infants.[2,6,7] Coffee is thought to decrease milk supply in some cultures, but there is no scientific information on coffee and milk supply.[8] Other sources of caffeine, such as cola and energy drinks, yerba mate or guarana, will have similar dose-related effects on the breastfed infant. Coffee intake of more than 450 mL daily may decrease breastmilk iron concentrations and result in mild iron deficiency anemia in some breastfed infants.[9]