Strength and Limitations
Our study included more infants than previous studies and followed growth velocity for a longer duration. The study is the first to report plasma fatty acid distribution after feeding hindmilk. Our study has several limitations to acknowledge. First, the study did not have a control group to compare growth anthropometrics and fatty acids, so it is not known how much of the infants’ growth improvements were due to the hindmilk intervention and how much might have occurred without the intervention. Randomization or having a control group for the infants with suboptimal growth velocity was not logistically feasible or ethical in our NICU settings, because hindmilk was part of standardized practice guidelines that aim to optimize postnatal growth. It is worth noting that the only change for the infants in our cohort was the hindmilk, and there were no other changes to their diet. Second, due to logistical challenges, we analyzed the samples of composite milk and hindmilk at the beginning of the study only and before fortification. A more frequent and comprehensive analysis is required in future studies. Third, we did not perform body composition or magnetic resonance imaging to identify if hindmilk alters the body’s fat mass, fat-free mass, or brain volume and connectivity. Fourth, we did not follow up regarding the long-term growth or neurodevelopmental outcomes. Long-term follow-up studies are needed to further understand the impact of feeding fortified hindmilk.