There is a wide range of charts available for the assessment of estimated foetal weight (EFW) and measured neonatal weight centiles at a given gestational age. Charts vary in methodology, with descriptive and prescriptive, population and customised versions available, many designed with a high risk of bias. In many countries, including the UK, operators use varied charts for prenatal and neonatal care, leading to disagreement on diagnosis of abnormal growth. In determining which chart to apply in our tertiary centre and potentially nationwide, we aimed to identify a chart package that is applicable to our population, offers charts for assessment of EFW, actual birthweight and fundal height and is concordant with the UK-WHO birthweight charts recommended nationally by the Royal College of Paediatrics and Child Health (RCPCH—rcpch.ac.uk) which are based on British growth reference centiles derived by Cole in 1990. Such concordance should facilitate agreement on small or large sizes, including the presence of growth restriction, between obstetricians and neonatologists, improving continuity of care with regard to the risk of perinatal morbidity and mortality. The INTERGROWTH-21st package offers both foetal and neonatal charts and has previously shown good continuity of growth between prenatal and neonatal centiles at late pre-term and term gestations in these populations when EFW in grams was calculated using both their formula including head and abdominal circumference only, or the Hadlock's formula, using three parameters (head, abdominal circumference and femur length). INTERGROWTH-21st prenatal chart centiles have also been shown to adequately fit the distribution of a large French prospective sample of ultrasound-derived foetal measurements. Here, we describe work to evaluate whether the INTERGROWTH-21st birthweight centiles are concordant with those of the UK-WHO birthweight charts for pre-term and term births.