I believe there is some reason for concern for preterm infants. Please see the article: Transmission of cytomegalovirus to preterm infants through breast milk by: Vochem,Hamprecht,Jahn, and Speer found in The Pediatric Infectious Disease Journal Vol. 17,No. 1, January,1998. It concluded that "There is evidence that the most immature infants are at the greatest risk to acquire an early and symptomatic CMV infection". (Italic's mine) 67 preterm infants were studied. 27 women were CMV-seronegative @ birth and breastmilk and infant's urine remained neg. 29 women were CMV IgG-seropositive with 23 of 27 of these mothers excreeting CMV in their milk. CMV infections occurred in 17 of the 67 with the 17 coming from seropositive mothers who excreted CMV and breastfed. Janet Bryant RN,IBCLC