In most instances provision of mother’s own milk is optimal. The few circumstances in which mother’s own milk should not be provided are discussed in Chapter 15, Circumstances when breastfeeding is contraindicated. While it is certainly plausible that premature infants with their immature immune systems are more vulnerable to infection, in most cases data regarding differences between premature and term infants in susceptibility to milk-associated infections are lacking. This section will focus on contraindications specific to premature infants.