We found that overfeeding infants 5 or more times in the first day of life significantly increases the risk for being overweight or obese at a child’s 4th year well child check. Although current guidelines for the proper volume of formula a newborn should receive are available, these guidelines are not widely enforced or followed by hospital personnel and new parents, placing the newborn at for future overweight or obesity. Furthermore, formula companies advise newborns consume 2-3 oz (60-90 ml) every 3 hours in their first weeks of life, which is significantly greater than what the literature recommends in the first day of life. 13-15 .
A longitudinal study based in Australia by Oddi et al. followed 2868 live births and the subsequent early feeding practices during their first months of life, and found that early feeding practices have a significant effect on long-term BMI and adiposity. 16 This study suggests that rapid early growth in life and early BMI trajectory is a risk factor for continued and later increased adiposity. 16 Although this study mainly focused on formula feeding as compared to breastfeeding resulting in more rapid weight gain during infancy, the same idea of rapid weight gain due to overfeeding may be able to be applied as elucidated in our study.
Additionally, Du, Hosada, Umekawa et al. investigated the effects of early overfeeding of mice pups of the C57BL/6N breed, the most commonly used general purpose strain of mice. Pups that were fed a high fat diet, had on postnatal weight gain in comparison to pups that were fed under normal conditions. 17 The effects of these different feeding conditions on glucose metabolism were measured on post-natal day 7, 14, and 21. 17 Unsurprisingly, the weight gains of the overfed and pups fed a high fat diet were 1.2 times greater than the control diet pups. 17 Interestingly, however, the overfed pups were found to have both higher blood glucose and serum insulin levels compared to that of the control group of pups, while the high fat diet pups only had higher blood glucose levels than the control. 17 Insulin resistance was also found in the overfed and high fat diet pups.
A similar investigation explored underfed, typically fed, and overfed rats and determined that by as early as day 15 of life, changes in metabolic pathways of these rats had already formed and were found to persist into adulthood in a way that significantly increased the chances for overweight and obesity. 3 This study also suggests that that hyperinsulinemia induced by the overfeeding has critical effects on the developing brain and may also contribute to later overweight and obesity. Overall, these studies support the idea that early environmental stimuli can have lasting metabolic changes and promote a trajectory of overweight or obesity. 3
Guidelines suggesting that newborn infants receive no more than 30mL per feed during DOL1 may be a critical addition to the prevention of overweight and obesity in children and adolescents. We hypothesized that feeding habits demonstrated in the first day of life could be indicative of future feeding habits that extend into childhood and could be a risk factor for becoming overweight or obese.
The Baby-friendly Hospital initiative (BFHI) was created in 1991 by the WHO and UNICEF to promote and support breastfeeding. Currently, over 152 countries are compliant with this initiative and have earned Baby-friendly designation. 18 The institution in the current study adopted this mission and earned Baby-Friendly designation in 2012. Although this initiative promotes exclusive breastfeeding for the first six months, it also promotes healthy feeding practices among formula fed newborns if the mother is unable or chooses not to breastfeed. As part of this initiative, our institution noticed the pattern of overfeeding and introduced a potential solution. Historically, mothers of formula fed newborns were given a 60mL ready-made bottle of formula with little instruction on the proper volume to feed. Many families were feeding the full 60 ml at each feeding often resulting in frequent emesis and baby discomfort. As previously discussed, this volume far exceeds the physiologic capacity of the newborn stomach on DOL1. In an attempt to improve this issue our institution now gives families specific instructions on proper volumes to feed on each day of life and provides a separate bottle to pour formula into before beginning a feed.
Our study has several limitations. Firstly, we only included babies with complete DOL1 formula feeding data, and who had at least 2 complete well child visits during the study period. Data from children who followed up at outside institutions could not be followed. Secondly, we did not have a control group, or include breast fed babies due to inability to track specific volumes. Finally, obesity is a multifactorial disease with many contributing factors such as genetics, family lifestyle, culture, inactivity, unhealthy diet, medical problems and social or economic issues. While we attempted adjust our analyses for these covariates, it is likely, that not all the covariance were removed. For example, we did not include factors such as maternal BMI and weight gain during pregnancy which may be of importance for risk of future overweight or obesity.
Our cohort included newborns who were born prior to the hospitals adoption of the BFHI, and introduction of separate bottles for portion control. Future studies should investigate whether this initiative has had an impactful reduction in newborn over-nutrition and subsequent reduced risk for overweight and obesity at follow-up outpatient care visits. Other future directions of this ongoing study includes looking at feeding trends in general over time from 2007 to current 2018 data. We hope to study feed intervals more closely as a risk factor for obesity later in life. For example, some newborns may have not met our criteria for an overfeed, however; may have been overall overfed due to increased frequency of feeds. Finally, we hope to follow our cohort over time as obesity may present at later ages.
In conclusion, we have shown that overfeeding on the first day of life is an independent risk factor for the development of overweight and obesity. Reinforcing newborn feeding guidelines to hospital personnel and new parents may be a critical component in confronting the childhood and adolescent obesity epidemic.