Macronutrients in Lactating NICU Parents - Impact of Kangaroo Care

Inclusion Criteria: Lactating Parent/Infant Dyads: 1. Lactating parents of infants who are currently admitted to the UCDMC NICU and are expected to remain in the NICU for at least 2 weeks from study enrollment 2. Lactating parent is 18 years of age or older 3. Infant with prematurity or other conditions prohibiting nutritive feeding at the breast during the study period 4. Lactating parent plans to feed their infants breast milk for at least 1 month 5. Lactating parent is willing to refrain from tandem feeding another child during the study period 6. Willing to refrain from enrolling infant in an interventional research study that may impact growth or feeding tolerance during the study period 7. Lactating parent is willing to use a hospital grade pump available in the NICU to express milk for sample collection 8. Lactating Parent that is willing to travel to UCDMC on 4 occasions within a 10 day period for study visits Providers/staff: 1\. Physicians, nurses, fellows, residents, and NICU staff involved in the implementation of Kangaroo care for the MILK study. Exclusion Criteria: 1. Infant less than 1 week of age at enrollment 2. Lactating parents expressing breast milk for more than one infant 3. Lactating parents who are currently or plan to tandem feed another child during the study period 4. Lactating parents that are participating in an interventional research study that could influence breast milk production. 5. Lactating parents with infants deemed by primary investigator/primary care team to be too unstable for kangaroo care 6. Lactating parents that are unwilling to participate in kangaroo care 7. Dyads that have participated in nutritive feeding at the breast 8. Lactating parents that use recreational drugs that contraindicate breastfeeding/provision of breast milk 9. Lactating parents taking therapies, supplements, or medications that are incompatible with breastfeeding/provision of breast milk to their infant 10. Lactating parents using, or planning to use, any over-the-counter or prescription medication for the purpose of increasing milk supply (including domperidone, fenugreek, turmeric, blessed milk thistle, Brewer's yeast, or lactation cookies) 11. Lactating parents that are involuntarily confined 12. Lactating parents that are adults unable to consent 13. Lactating parents unwilling to travel to UC Davis NICU for study visits 14. Anyone deemed unfit for participation by the investigator(s)