The intrapartum acid-base status of the fetus is an important component in establishing the link between intrapartum events and neonatal condition. The analysis of cord blood gases from the umbilical artery is believed to be the best representation of the fetal acid-base status immediately before birth. Blood gas analysis is able to objectively confirm or exclude the presence of damaging acidemia. Although measurements may be affected by several factors related to the method of sampling, storage, and assessment, a wide margin of accuracy exists when prompt assessment is unavailable. Because a substantial deviation from the standard procedure is required before a sample is alleged to be imprecise, it is unlikely that standard sampling methods would be ineligible in litigation.
Isaac, B., & Tamar, G. (2007). Umbilical Cord Blood Gases. Clinics in Perinatology, 34(3), 451–459. https://doi.org/10.1016/j.clp.2007.05.001