BACKGROUND: The DoHAD hypothesis suggests that preterm infants should achieve similar growth and body composition to healthy term-born infants in order to minimize disease risk. Postnatal growth of preterm infants is not fully understood and requires additional characterization, particularly in terms of differences to and transition from intrauterine growth. The period of postnatal adaptation to extrauterine life has been described in preterm infants by Rochow et al., 2016 and was seen to last 21 days. During these first 21 days of life, preterm infants experience a physiological, one-time, permanent contraction of extracellular water spaces (water loss), which causes a downward shift in the growth trajectories. This period of adaptation/water loss and the transition to extrauterine growth rates to achieve WHOGS target trajectories need to be incorporated into individual reference curves for preterm infants.
OBJECTIVES: To develop and evaluate approaches to establish individualized growth trajectories for preterm infants to achieve growth similar to the WHO growth standards (WHOGS) for healthy infants at term, using recently published data about the physiological postnatal adaptation.
METHODS: Two approaches were compared: 1) Postnatal-Percentile Approach: growth following the percentile at day of life (DOL) 21 until term; 2) Growth-Velocity Approach: using day-specific Fenton median growth velocities between DOL 21 and term. The impact of these approaches were compared using body compositions of 57 healthy preterm infants obtained before discharge (36+0/7 to 42+6/7 weeks PMA).
The main outcome was the weight difference between the predicted trajectory and WHOGS target at 42+0/7 weeks PMA for the infants’ birth weight percentile.
RESULTS: Postnatal-Percentile Approach: Trajectories deviated by up to 930g and did not match with WHOGS. Growth-Velocity Approach: Trajectories converged with term WHOGS after adjusting growth velocities with a factor of 1.0017 (approximately 10% increase in daily growth velocities). The validation of the Growth-Velocity Approach in preterm infants with minimal medical interventions revealed little deviation between predicted and actual weights. Infants were symmetrically distributed around zero deviation with a mean deviation of -10±370g and an average of 20% fat mass. In contrast, the Postnatal-Percentile Approach showed large deviations between predicted and actual weights and a skewed distribution around zero deviation with a mean deviation of -310±380g or 70±350g, following the birth or DOL 21 percentile, respectively.
CONCLUSIONS: Individualized growth trajectories for preterm infants converged with the WHOGS when Fenton daily median growth velocities were applied and optimized with a single factor. The simplicity of the model and its ability to predict target weights that correspond to an appropriate fat mass suggests a biological principle. These results provide a superior understanding of preterm infant’s growth including the physiological postnatal adaptation and new trajectories to achieve WHOGS target trajectories. Results can be used to develop a bedside tool to aid clinicians in monitoring growth, guiding nutrition and preventing chronic adult diseases as a consequence of unguided, inappropriate growth. / Thesis / Master of Science (MSc) / It has been well established that growth of preterm infants has a long-term impact on health in adulthood. Since the survivability of preterm infants has drastically improved in the last decades, there has been a shift in focus to improving quality of life, including improved growth. Infants that grow too quickly or too slowly may develop inappropriate body compositions, with either too much or too little fat. A sub-optimal body composition can put infants at an increased risk for developing cardiovascular, metabolic or neurodevelopmental diseases later in life. In order to prevent these diseases and optimize growth, it is necessary to have a better understanding of how preterm infants should grow. This thesis aims to improve the characterization of growth for preterm infants by providing individual reference growth trajectories for preterm infants that take into consideration postnatal adaptation and aim to minimize later disease risk.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/19893 |
| Date | January 2016 |
| Creators | Landau-Crangle, Erin |
| Contributors | Fusch, Christoph, Medical Sciences |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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