The goal of this study is to learn if InfaCore (IC) an energy and nutrient dense formulation (ENDF) can improve growth and tolerance in infants with or at risk of growth faltering when fed IC.

Rationale: The definition of FG/FTT was established by a group of experts in a report published in 2023 (Cooke et al., 2023). In this report they agreed a fall in weight-for-age z-score (WAZ) of ≥1.0 SD over a period of 1 or more months (excluding the first 2 weeks after birth) which includes at least 2-3 growth measurements (Cooke et al., 2023). It is also important to consider infants at risk who have static weight for extended periods e.g., >/=4 weeks. FG/FTT affects different populations and is estimated to be 10% of infants globally.

InfaCore (IC) an energy and nutrient dense formulation is indicated for infants and young children with FG/FTT defined above or for those at risk of developing e.g., with static weight for extended periods. At risk infants might include some or all of the following those with congenital heart disease (CHD) admitted for surgical procedures, those with critical illness (CI) or on the PICU, infants cystic fibrosis (CF) or other respiratory conditions including chronic lung disease (CLD), some forms of severe cerebral palsy (CP), and those requiring a surgical procedure or post-surgery.

Objective: To demonstrate growth and tolerance in infants with or at risk of growth faltering when fed IC an Energy and Nutrient Dense Formula (ENDF).

Study design: A prospective, single-centre, single-arm open label pilot study to show growth and tolerance in infants with/at risk of FG/FTT when fed an ENDF for 8 weeks.

Inclusion Criteria:

• Infants aged from 1 month to </=12 months of age
• Infants taking at least 50% of daily intake from infant formula
• Diagnosis of FG (a fall in WAZ of ≥1.0 SD over 1 month or more - not including the first 2 weeks after birth) or risk of FG (static weight for >/= 1 month)
• Infants >/=37 weeks gestation at time of recruitment
• Parent/ legal guardian willing to provide written informed consent

Exclusion Criteria:

• Exclusively Breastfed infants
• Infants with other medical problems that might independently affect intake (oral or otherwise) or who have specific nutrient needs not met by IC e.g. some gastrointestinal malformations, some renal and liver conditions, inborn errors of metabolism, galactosemia
• Infants on total parenteral nutrition
• Infants with cow milk protein allergy
• Infants with soy allergy
• Infants who participated in other studies within 2 weeks prior to recruitment
• Situations where the investigator has concerns about the willingness or ability of the parents/caregivers to comply with protocol requirements
• Infants who are on a vegan diet
• Infants who are allergic to fish
• Infants born preterm <37 weeks gestation