Fetal biometry to assess the size and growth of the fetus.

Ultrasound assessment of fetal size is central to modern practice of prenatal care. It facilitates accurate pregnancy dating and screening for fetal growth disorders. This article discusses evidence-based recommended methods for pregnancy dating and biometric measurements. We address some confusing terms such as fetal growth "standards" and fetal growth "references" along with explaining the differences between prescriptive and descriptive charts and between growth charts based on estimated fetal weight vs those based on birth weight. Opinions remain divided on which charts are best to use; however, since the publication of the Intergrowth 21st study, we are now in a position to be able to assess growth and development in an internationally standardized fashion, from fetal life up to 5 years of age. A universal quality control policy can help maintain the high standard of ultrasonography required to achieve an acceptable level of diagnostic accuracy for fetal growth disorders.