This version was machine-translated from German and has not been medically reviewed. The authoritative version is the German version.
Preterm infants
14 calculators · Fenton, Olsen, birth length, weight gain, NICHD outcomes of extremely preterm infants
This category brings together growth calculators and prediction aids for preterm infants. You will find the Fenton curves of 2003, 2013 and 2025 (each with a trajectory display for several measurement points), the intrauterine curves according to Olsen 2010, the Olsen 2015 BMI calculator and the classification of birth weight as SGA, AGA or LGA according to Fenton, Olsen and INTERGROWTH-21st. Also included are the calculator for growth velocity and required weight gain and the NICHD outcome calculator for extremely preterm infants (Rysavy 2020). Each calculator states its formula and sources so that you can follow the calculation.
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Fenton 2025 Growth Calculator / Fenton 2025 Growth Calculator
Weight, length, head circumference according to the third-generation Fenton curves (2025); expected weight gain -
Fenton 2025 Electronic Growth Chart / Electronic Fenton 2025 Growth Chart
Longitudinal course with curves and weight gain per week -
Fenton 2013 Growth Calculator / Fenton 2013 Growth Calculator
Weight, length, head circumference by postmenstrual age; expected weight gain -
Fenton 2013 Electronic Growth Chart / Electronic Fenton 2013 Growth Chart
Longitudinal course with curves and weight gain per week -
Fenton 2003 Growth Calculator / Fenton 2003 Growth Calculator (Legacy)
Older preterm growth charts (2003, unisex) – for comparison with Fenton 2013 -
Olsen 2010 Growth Calculator
Intrauterine curves (USA): weight, length, head circumference 23–41 weeks -
Olsen 2015 BMI Calculator
BMI percentile and z-score for preterm infants 24–41 weeks -
INTERGROWTH-21st size at birth (33+0 to 42+6 weeks)
Birth weight, length and head circumference according to the INTERGROWTH-21st standard, with z-score and SGA/LGA -
INTERGROWTH-21st size at birth of very preterm infants (24+0 to 32+6 weeks)
Birth weight, length and head circumference of very preterm infants according to INTERGROWTH-21st, with z-score and SGA/LGA -
INTERGROWTH-21st postnatal growth of preterm infants
Weight, length, head circumference and weight for length 27–64 weeks postmenstrual; gain needed to hold the percentile -
INTERGROWTH-21st growth chart for preterm infants (follow-up)
Multiple measurement points of a preterm infant on the INTERGROWTH-21st postnatal curves -
Size at birth (SGA/AGA/LGA)
Classify birth weight by Fenton 2013, Fenton 2025, Olsen 2010 and INTERGROWTH-21st -
Growth velocity & required gain
g/kg/day between two measurements; weekly gain to maintain the percentile (Fenton 2013) -
NICHD Extremely Preterm Birth Outcome Tool (22–25 weeks)
Survival probability of actively treated and of all extremely preterm infants from gestational age, birth weight, sex, multiple-birth status and steroids (Rysavy 2020) – with neurodevelopmental data
Frequently asked questions
Which percentile curve for preterm infants?
The Fenton 2025 growth calculator provides percentiles and z-score for weight, length and head circumference from 22.5 to 50 weeks postmenstrual age. Fenton 2013, Fenton 2003 (legacy) and Olsen 2010 are also available for comparison.
How much weight gain does a preterm infant need to stay on the same percentile?
The Fenton 2025 growth calculator shows the weekly weight gain required to maintain the current percentile. The Growth Velocity & Required Gain calculator computes g/kg/day between two measurements according to Patel 2005 on the Fenton 2013 curve.
How do I classify birth weight as SGA, AGA or LGA?
The Size at Birth calculator compares birth weight with the cut-offs of Fenton 2013, Fenton 2025, Olsen 2010 and INTERGROWTH-21st and classifies it as SGA, AGA or LGA. For Fenton, the P3, P10, P90 and P97 apply for each completed week.