Register      Login

VOLUME 2 , ISSUE 3 ( July-September, 2023 ) > List of Articles


Umbilical Cord Blood Gases: Sampling, Evaluation, and Application for Clinicians

Mahesh Hiranandani, Inderjeet Kaur, Sudhanshu Grover

Keywords : Arterio-venous difference, ‘20, 30, 40, 50 rule’, Maternal hypoxemia, Base deficit, Birth asphyxia, Brain injury, Carbonic acid, Cerebral palsy, Cord blood gas, Eucapnic pH, pH qu 40, Hypercapnia, Hypoxic–ischemic encephalopathy, Maternal positioning, Neonatal encephalopathy, Nuchal cord, Organic acids, Oxygen-carrying capacity, Peripartum events, Placenta, Rectal temperature, Regional anesthesia, Respiratory acidosis, Stillbirth, Surveillance, Umbilical arteries, Umbilical venous blood, Vascular zone, Universal cord blood gas analysis

Citation Information : Hiranandani M, Kaur I, Grover S. Umbilical Cord Blood Gases: Sampling, Evaluation, and Application for Clinicians. 2023; 2 (3):214-221.

DOI: 10.5005/jp-journals-11002-0074

License: CC BY-NC 4.0

Published Online: 26-09-2023

Copyright Statement:  Copyright © 2023; The Author(s).


Predicting the severity of birth asphyxia-related brain injury in newborn infants is a difficult task. Cord blood gases can be useful indices in the assessment of the impact of peripartum events. Cord blood gas parameters are particularly important because, despite all the progress in fetal monitoring, the time gap between the onset of fetal heart rate (FHR) abnormalities and birth asphyxia-related brain injury has remained difficult to predict. In this paper, we have focused on cord blood gas values in understanding the degree of compromise. These data can help determine the timing of fetal compromise prior to labor, and whether these precipitating events were acute or prolonged. When combined with some adverse clinical markers, the accuracy of low-cord pH in predicting neonatal mortality and morbidity can be even higher. Low-cord pH or eucapnic neonatal pH can also help in the surveillance of at-risk infants and in timely institution of neuroprotective therapies. We present a detailed review on sampling, evaluation, and application of cord blood gas values for clinicians.

PDF Share
  1. Royal College of Obstetricians and Gynaecologists Clinical Effectiveness Support Unit. The use of electronic fetal monitoring: The use and interpretation of cardiotocography in intrapartum fetal surveillance. London: RCOG [cited 2001]. Available from:
  2. ACOG Committee Opinion No. 348. Umbilical cord blood gas and acid-base analysis. Obstet Gynecol 2006;108(5):1319–1322. DOI: 10.1097/00006250-200611000-00058.
  3. Ross MG. How and when umbilical cord gas analysis can justify your obstetric management. OBG Manag 2017;29(3):38–44, 46. Available from:
  4. Cantu J, Szychowski JM, Li X, et al. Predicting fetal academia using umbilical venous cord gas parameters. Obstet Gynecol 2014;124(5):926–932. DOI: 10.1097/AOG.0000000000000517.
  5. Blechner JN. Maternal–fetal acid–base physiology. Clin Obstet Gynecol 1993;36(1):3–12. DOI: 10.1097/00003081-199303000-00004.
  6. Aarnoudse JG, IIsley NP, Penfold P, et al. Permeability of human placenta to bicarbonate: In vitro perfusion studies. Br J Obstet Gynaecol 1984;91:1096. DOI: 10.1111/j.1471-0528.1984.tb15083.x.
  7. Ullrich JR, Ackerman BD. Changes in umbilical artery blood gas values with the onset of respiration. Biol Neonate 1972;20(5):466–474. DOI: 10.1159/000240488.
  8. Mokorami P, Wiberg N, Olofsson P. Hidden acidosis: An explanation of acid-base and lactate changes occurring in umbilical cord blood after delayed sampling. BJOG 2013;120(8):996–1002. DOI: 10.1111/1471-0528.12234.
  9. Armstrong L, Stenson B. Effect of delayed sampling on umbilical cord arterial and venous lactate and blood gases in clamped and unclamped vessels. Arch Dis Child Fetal Neonatal 2006;91(5):F342–F345. DOI: 10.1136/adc.2005.086744.
  10. Gaskins JE, Goldkrand JW. Air contamination in umbilical cord blood gas sampling. Am J Obstet Gynecol 1994;171(6):1546–1549. DOI: 10.1016/0002-9378(94)90399-9.
  11. Armstrong L, Stenson B. Use of umbilical cord blood gas analysis in the assessment of the newborn. Arch Dis Child Fetal Neonatal 2007;92(6):430–434. DOI: 10.1136/adc.2006.099846.
  12. Westgate J, Garibaldi J, Greene K. Umbilical cord blood gas analysis at delivery: A time for quality data. Br J Obstet Gynaecol 1994;101(12):1054–1063. DOI: 10.1111/j.1471-0528.1994.tb13581.x.
  13. Nudelman MJR, Belogolovsky E, Jegatheesan P, et al. Effect of delayed cord clamping on umbilical blood gas values in term newborns. Obstet Gynecol 2020;135(3):576–582. DOI: 10.1097/AOG.0000000000003663.
  14. Yeomans ER, Hauth JC, Gilstrap LC III, et al. Umbilical cord pH, PCO2, and bicarbonate following uncomplicated term vaginal deliveries. Am J Obst Gynecol 1985;151(6):798–800. DOI: 10.1016/0002-9378(85)90523-x.
  15. Wiberg N, Källén K, Olofsson P. Base deficit estimation in umbilical cord blood is influenced by gestational age, choice of fetal fluid compartment, and algorithm for calculation. Am J Obstet Gynecol 2006;195(6):1651–1656. DOI: 10.1016/j.ajog.2006.05.043.
  16. Ross MG, Gala R. Use of umbilical artery base excess: Algorithm for the timing of hypoxic injury. Am J Obstet Gynecol 2002;187(1):1–9. DOI: 10.1067/mob.2002.123204.
  17. Low JA, Pancham SR, Piercy WN, et al. Intrapartum fetal asphyxia: Clinical characteristics, diagnosis, and significance in relation to pattern of development. Am J Obstet Gynecol 1977;129(8):857–872. DOI: 10.1016/0002-9378(77)90519-1.
  18. Hagelin A, Leyon J. The effect of labor on the acid-base status of the newborn. Acta Obstet Gynecol Scand 1998;77(8):841–844. PMID: 9776598.
  19. Duerbeck NB, Chaffin DG, Seeds JW. A practical approach to umbilical artery pH and blood gas determinations. Obstet Gynecol 1992;79(6):959–962. PMID: 1579322.
  20. Johnson JW, Richards DS. The etiology of fetal acidosis as determined by umbilical cord acid-base studies. Am J Obstet Gynecol 1997;177(2):274–282. DOI: 10.1016/s0002-9378(97)70187-x.
  21. Martin GC, Green RS, Holzman IR. Acidosis in newborns with nuchal cords and normal Apgar scores. J Perinatol 2005;25(3):162–165. DOI: 10.1038/
  22. Nakamura KT, Smith BA, Erenberg A, et al. Changes in arterial blood gases following cardiac asystole during fetal life. Obstet Gynecol 1987;70(1):16–17. PMID: 3110712.
  23. Thorp JA, Sampson JE, Parisi VM, et al. Routine umbilical cord blood gas determinations? Am J Obstet Gynecol 1989;161(3):600–605. DOI: 10.1016/0002-9378(89)90362-1.
  24. Leung TY, Lok IH, Tam WH, et al. Deterioration in cord blood gas status during the second stage of labour is more rapid in the second twin than in the first twin. BJOG 2004;111(6):546–549. DOI: 10.1111/j.1471-0528.2004.00133.x.
  25. Atalla RK, Abrams K, Bell SC, et al. Newborn acidbase status and umbilical cord morphology. Obstet Gynecol 1998;92(5):865–868. DOI: 10.1016/s0029-7844(98)00316-0.
  26. Maher JT, Conti JA. A comparison of umbilical cord blood gas values between newborns with and without true knots. Obstet Gynecol 1996;88(5):863–866. DOI: 10.1016/0029-7844(96)00313-4.
  27. Wu YW, Colford JM Jr. Chorioamnionitis as a risk factor for cerebral palsy: A meta-analysis. JAMA 2000;284(11):1417–1424. DOI: 10.1001/jama.284.11.1417.
  28. Helwig JT, Parer JT, Kilpatrick SJ, et al. Umbilical cord blood acid-base state: What is normal? Am J Obstet Gynecol 1996;174(6):1807–1812;1812–1814. DOI: 10.1016/s0002-9378(96)70214-4.
  29. Weiner CP, Sipes SL, Wenstrom K. The effect of fetal age upon normal fetal laboratory values and venous pressure. Obstet Gynecol 1992;79(5 (Pt 1)):713–718. PMID: 1565354.
  30. HN Simhan. Umbilical cord blood gas analysis at delivery – UpToDate 2020. Available at:
  31. Martí Gamboa S, Pascual Mancho J, Rodrigo Rodríguez M, et al. pH, base deficit or lactate. Which is better for predicting neonatal morbidity? J Matern Fetal Neonatal Med 2017;30(19):2367–2371. DOI: 10.1080/14767058.2016.1248936.
  32. Low JA, Panagiotopoulos C, Derrick EJ. Newborn complications after intrapartum asphyxia with metabolic acidosis in the term fetus. Am J Obstet Gynecol 1994;170(4):1081–1087. DOI: 10.1016/s0002-9378(94)70101-6.
  33. Van den Berg PP, Nelen WL, Jongsma HW, et al. Neonatal complications in newborns with an umbilical artery pH, 7.00. Am J Obstet Gynecol 1996;175(5):1152–1157. DOI: 10.1016/s0002-9378(96)70021-2.
  34. Goodwin TM, Belai I, Hernandez P, et al. Asphyxial complications in the term newborn with severe umbilical acidemia. Am J Obstet Gynecol 1992;167(6):1506–1512. DOI: 10.1016/0002-9378(92)91728-s.
  35. Kurinczuk JJ, White-Koning M, Badawi N. Epidemiology of neonatal encephalopathy and hypoxic-ischaemic encephalopathy. Early Hum Dev 2010;86(6):329–38. DOI: 10.1016/j.earlhumdev.2010.05.010.
  36. Volpe JJ. Neonatal encephalopathy: An inadequate term for hypoxic-ischemic encephalopathy. Ann Neurol 2012;72(2):156–166. DOI: 10.1002/ana.23647.
  37. Graham EM, Ruis KA, Hartman AL, et al. A systematic review of role of the intrapartum hypoxia-ischemia in causation of neonatal encephalopathy. Am J Obstet Gynecol 2008;199(6):587–595. DOI: 10.1016/j.ajog.2008.06.094.
  38. Molloy EJ, Bearer C. Neonatal encephalopathy versus hypoxic-ischemic encephalopathy. Pediatr Res 2018;84(5):574. DOI: 10.1038/s41390-018-0169-7.
  39. Dammann O, Ferriero D, Gressens P. Neonatal encephalopathy or hypoxic-ischemic encephalopathy? Appropriate terminology matters Pediatr Res 2011;70(1):1–2. DOI: 10.1203/PDR.0b013e318223f38d.
  40. Nelson KB, Leviton A. How much of neonatal encephalopathy is due to birth asphyxia? Am J Dis Child 1991;145(11):1325–1331. DOI: 10.1001/archpedi.1991.02160110117034.
  41. American College of Obstetricians and Gynecologists (ACOG) and American Academy of Pediatrics (AAP). Neonatal encephalopathy and neurologic outcome, Second Edition. ACOG, Obstet Gynecol 2014;123(4):896–901. Available at:
  42. MacLenan AH, Thompson SC. Cerebral palsy: Causes, pathways and the role of genetic variants. Am J Obstet Gynecol 2015;213(6):779–788. DOI: 10.1016/j.ajog.2015.05.034.
  43. Perlman J. Intrapartum hypoxic-ischemic cerebral injury and subsequent cerebral palsy. Pediatrics 1997;99(6):851–859. DOI: 10.1542/peds.99.6.851.
  44. Peliowski-Davidovich A. Hypothermia for newborns with hypoxic ischemic encephalopathy. Paediatr Child Health 2012;17(1):41–44. DOI: 10.1093/pch/17.1.41.
  45. Yeh P, Emary K, Impey L. The relationship between umbilical cord arterial pH and serious adverse neonatal outcome: Analysis of 51,519 consecutive validated samples. BJOG 2012;119(7):824–831. DOI: 10.1111/j.1471-0528.2012.03335.x.
  46. Malin GL, Morris RK, Khan KS. Strength of association between umbilical cord pH and perinatal and long term outcomes: Systematic review and meta-analysis. BMJ 2010;340:c1471. DOI: 10.1136/bmj.c1471.
  47. Svirko, Mellanby J, Impey L. The association between cord pH at birth and intellectual function in childhood. Early Hum Dev 2008;84(1): 37–41. DOI: 10.1016/j.earlhumdev.2007.02.002.
  48. King TA, Jackson GL, Josey AS, et al. The effect of profound umbilical artery acidemia in term neonates admitted to a newborn nursery. J Pediatr 1998;132(4):624–629. DOI: 10.1016/s0022-3476(98)70350-6.
  49. Hafström M, Ehnberg S, Blad S, et al. Developmental outcome at 6.5 years after acidosis in term newborns: A population-based study. Pediatrics 2012;129(6):e1501–e1507. DOI: 10.1542/peds.2011-2831.
  50. Sabol BA, Caughey AB. Acidemia in neonates with a 5-minute Apgar score of 7 or greater-What are the outcomes? Am J Obstet Gynecol 2016;215(4):486.e1–486.e6. DOI: 10.1016/j.ajog.2016.05.035.
  51. Knutzen L, Svirko E, Impey L. The significance of base deficit in acidemic term neonates. Am J Obstet Gynecol 2015;213(03):373.e1–373.e7. DOI: 10.1016/j.ajog.2015.03.051.
  52. Georgieva A, Moulden M, Redman CW. Umbilical cord gases in relation to the neonatal condition: the EveREst plot. Eur J Obstet Gynecol Reprod Biol 2013;168(02):155–160. DOI: 10.1016/j.ejogrb.2013.01.003.
  53. Cottee C, Harding K. Risk management in obstetrics. Obstet, Gynaecol Reprod Med 2008;18:155–62. DOI: 10.1016/j.ogrm.2008.04.003.
  54. Ferreira CS, Melo A, Fachada AH, et al. Umbilical cord blood gas analysis, obstetric performance and perinatal Outcome. Rev Bras Ginecol Obstet 2018;40(12):740–748. DOI: 10.1055/s-0038-1675187.
  55. Goldaber KG, Gilstrap LC 3rd, Leveno KJ, et al. Pathologic fetal acidemia. Obstet Gynecol 1991;78(6):1103–1107. PMID: 1945216.
  56. Low JA, Lindsay BG, Derrick EJ. Threshold of metabolic acidosis associated with newborn complications. Am J Obstet Gynecol 1997;177(6):1391–1394. DOI: 10.1016/s0002-9378(97)70080-2.
  57. Low JA, Panagiotopoulos C, Derrick EJ. Newborn complications after intrapartum asphyxia with metabolic acidosis in the preterm fetus. Am J Obstet Gynecol 1995;172(3):805–810. DOI: 10.1016/0002-9378(95)90003-9.
  58. Perlman JM, Risser R. Can asphyxiated infants at risk for neonatal seizures be rapidly identified by current high-risk markers? Pediatrics 1996;97(4):456–462. PMID: 8632928.
  59. Piquard F, Schaefer A, Dellenbach P, et al. Is fetal acidosis in the human fetus maternogenic during labor? A reanalysis. Am J Physiol 1991;261:R1294–R1299. DOI: 10.1152/ajpregu.1991.261.5.R1294.
  60. Kruger K, Kublickas M, Westgren M. Lactate in scalp and cord blood from fetuses with ominous fetal heart rate patterns. Obstet Gynecol 1998;92(6):918–922. DOI: 10.1016/s0029-7844(98)00347-0.
  61. Natesan SR. Routine measurements of cord arterial blood lactate levels in infants delivering at term and prediction of neonatal outcome. Med J Malaysia 2016;71(3):131–133. PMID: 27495887.
  62. Chou YH, Tsou Yau KI, Wang PJ. Clinical application of the measurement of cord plasma lactate and pyruvate in the assessment of high-risk neonates. Acta Paediatr 1998;87(7):764–768. DOI: 10.1080/080352598750013851.
  63. Allanson ER, Waqar T, White C, et al. Umbilical lactate as a measure of acidosis and predictor of neonatal risk: A systematic review. BJOG 2017;124(4):584–594. DOI: 10.1111/1471-0528.14306.
  64. Tuuli MG, Stout MJ, Shanks A, et al. Umbilical cord arterial lactate compared with pH for predicting neonatal morbidity at term. Obstet Gynecol 2014;124(4):756–761. DOI: 10.1097/AOG.0000000000000466.
  65. Swanson K, Whelan AR, Grobman WA, et al. Can venous cord gas values predict fetal acidemia? Am J Obstet Gynecol 2017;217(3):364.e361–364.e365. DOI: 10.1016/j.ajog.2017.05.047.
  66. Harris M, Beckley SL, Garibaldi JM, et al. Umbilical cord blood gas analysis at the time of delivery. Midwifery 1996;12(3):146–150. DOI: 10.1016/s0266-6138(96)90059-5.
  67. Kelly R, Ramaiah S, Sheridan H, et al. Dose-dependent relationship between acidosis at birth and likelihood of death or cerebral palsy. Arch Dis Child Fetal Neonatal Ed 2018;103:F567–F572. DOI: 10.1136/archdischild-2017-314034.
  68. Vesoulis ZA, Liao SM, Rao R, et al. Re-examining the arterial cord blood gas pH screening criteria in neonatal encephalopathy. Arch Dis Child Fetal Neonatal Ed 2018;103(4):F377–F382. DOI: 10.1136/archdischild-2017-313078.
  69. Sailing E, Schmidt S. In response to the article by Racinet C et al. Neonatal acidosis at birth: In search of a reliable marker. Gynecol Obstet Fertil 2016;44:730–731. DOI: 10.1016/j.gyobfe.2016.04.005.
  70. Andersen OS, Engel K. A new acid base nomogram. An improved method for calculation of the relevant blood acid base data. Scand J Clin Lab Invest 12960;12:177–186. DOI: 10.3109/00365516009062420.
  71. Racinet C, Ouellet P, Muraskas J, et al. Neonatal cord blood eucapnic pH: A potential biomarker predicting the need for transfer to the NICU. Arch Pédiatr 2020;27(1):6–11. DOI: 10.1016/j.arcped.2019.10.013.
  72. Blickstein I, Green T. Umbilical cord blood gases. Clin Perinatol 2007;34(3):451–459. DOI: 10.1016/j.clp.2007.05.001.
  73. White CRH, Doherty DA, Henderson JJ, et al. Benefits of introducing universal cord blood gas and lactate analysis into an obstetric unit. Aust New Z J Obstet Gynaecol 2010;50(4):318–328. DOI: 10.1111/j.1479-828X.2010.01192.x.
  74. Thorp JA, Rushing RS. Umbilical cord blood gas analysis. Obstet Gynecol Clin North Am 1999;26(4):695–709. DOI: 10.1016/s0889-8545(05)70107-8.
PDF Share
PDF Share

© Jaypee Brothers Medical Publishers (P) LTD.