An Attempt to Standardize the Calculation of Growth Velocity of Preterm Infants-Evaluation of Practical Bedside...

Area of Science:

• Neonatalogy
• Pediatric Growth Assessment
• Infant Nutrition

Background:

• Accurate growth assessment in preterm infants is crucial for monitoring development and health outcomes.
• Existing growth velocity recommendations are often based on general population data and may not accurately reflect preterm infant trajectories.
• Several growth references, including Fenton 2013, Olsen 2010, INTERGROWTH 2015, and WHO Growth Standard 2006, are used for preterm infants.

Purpose of the Study:

• To evaluate the concordance between established growth velocity recommendations and current growth references for preterm infants.
• To determine the time periods during which commonly cited growth rates (e.g., 15 g/kg/d, 10-30 g/day, 1 cm/week) align with established preterm growth charts.
• To provide evidence-based insights for refining growth monitoring guidelines in preterm populations.

Main Methods:

• Calculation of weight gain velocities using Average (2-point), Exponential (2-point), and Early (1-point) methods over 1-16 week periods.
• Graphical illustration of weekly growth velocities (g/kg/d, g/day, cm/week) against Fenton 2013, Olsen 2010, INTERGROWTH 2015, and WHO 2006 references.
• Superimposition of frequently-quoted rates (15 g/kg/d, 10-30 g/day, 1 cm/week) onto growth charts, with specific analysis for 15 g/kg/d and 1 cm/week from 24-50 weeks.

Main Results:

• Average and Exponential methods for g/kg/d showed good agreement (5.0-18.9 g/kg/d), while the Early method produced higher values (up to 41 g/kg/d).
• Preterm growth references aligned with the 15 g/kg/d rate around 34 weeks, but showed higher rates before and lower rates after this point.
• Observed head and length growth rates generally fit the 1 cm/week velocity between 23-30 weeks and 37-40 weeks, respectively. Calculated g/kg/d curves diverged from growth charts, crossing medians near term.

Conclusions:

• Standard growth velocity recommendations (15 g/kg/d, 10-30 g/day, 1 cm/week) are only applicable to specific, limited periods in preterm infant growth.
• Growth rates of 15-20 g/kg/d, calculated via average or exponential methods, are appropriate targets for infants aged 23-36 weeks but not beyond.
• The findings highlight the need for nuanced, age-specific growth velocity targets for preterm infants to ensure accurate monitoring and care.