This version was machine-translated from German and has not been medically reviewed. The authoritative version is the German version.

Size at birth (SGA/AGA/LGA)

Classify birth weight by Fenton 2013, Fenton 2025, and INTERGROWTH-21st

About this calculator

Compares the birth weight with the cutoffs of several references (Fenton 2013 and 2025: P3/P10/P90/P97 per completed week; INTERGROWTH-21st: to the day) and classifies SGA, AGA, or LGA.

Sources

International standards for newborn weight, length, and head circumference by gestational age and sex: the Newborn Cross-Sectional Study of the INTERGROWTH-21st Project (Lancet 384:857–868) – Villar J, Cheikh Ismail L, Victora CG et al., University of Oxford (2014) Link
INTERGROWTH-21st very preterm size at birth reference charts (Lancet 387:844–845) – Villar J, Giuliani F, Fenton TR et al., University of Oxford (2016) Link
A systematic review and meta-analysis to revise the Fenton growth chart for preterm infants (BMC Pediatr 13:59) – table of birth weight limits P3/P10/P90 – Fenton TR, Kim JH, University of Calgary (2013) Link
Fenton Third-Generation Growth Charts of Preterm Infants Without Abnormal Fetal Growth: A Systematic Review and Meta-Analysis (Paediatr Perinat Epidemiol 39:543–555) – table of birth weight limits P3/P10/P90/P97 – Fenton TR et al., University of Calgary (2025) Link
Definition of SGA (small for gestational age) and LGA (large for gestational age): birth weight below P10 and above P90 respectively for gestational age – World Health Organization (WHO) / INTERGROWTH-21st (2014) Link

Found an error or have an idea?

Tell us if something does not work or could be better.

Give feedback

Reference and license

Fenton 2013 – weight 22.5–50 weeks; length and head circumference 23.5–50 weeks.
Fenton TR, Kim JH. A systematic review and meta-analysis to revise the Fenton growth chart for preterm infants. BMC Pediatr. 2013;13:59. License: CC BY-NC-ND 4.0 (Dr. Tanis Fenton, University of Calgary) – non-commercial use only; commercial license via Innovate Calgary. Source
LMS parameters from the official Excel calculator “clinical exact age calculator v7”. For classification at birth (SGA/AGA/LGA), completed weeks are decisive; for follow-up, the exact postmenstrual age.
Olsen 2010 – 23–41 completed weeks.
Olsen IE, Groveman SA, Lawson ML, Clark RH, Zemel BS. New intrauterine growth curves based on United States data. Pediatrics. 2010;125(2):e214–e224. License: publication (AAP); LMS tables from the R package childsds (GPL). Source
Support points for each completed week of gestation; values between weeks are linearly interpolated.

Related calculators

Note

Calculation aid for healthcare professionals. Percentiles and z-scores describe the position of a measured value in the reference population; clinical assessment remains with the treating physician.

Frequently asked questions

Which reference should be used for classification at birth?

That depends on the question: Fenton (2013 or 2025) is widely used in neonatology, INTERGROWTH-21st is an international standard with percentiles to the exact day. The calculator shows all of them side by side so that the classification remains traceable.