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VOLUME 25 , ISSUE S3 ( December, 2021 ) > List of Articles


Fetomaternal Acid–Base Balance and Electrolytes during Pregnancy

Armin Ahmed

Keywords : Acid–base disturbance, Electrolytes in pregnancy, Hypercalcemia in pregnancy, Hypernatremia in pregnancy, Hypocalcemia in pregnancy, Hyponatremia in pregnancy

Citation Information :

DOI: 10.5005/jp-journals-10071-24030

License: CC BY-NC 4.0

Published Online: 12-01-2022

Copyright Statement:  Copyright © 2021; The Author(s).


A pregnant mother undergoes significant changes in acid-base status as well as sodium and calcium metabolism to combat her physiological needs of pregnancy. Pregnant patients experience mild respiratory alkalosis due to the stimulation of the respiratory center by progesterone. This is associated with a corresponding increase in bicarbonate excretion by kidneys; as a result, the pH remains slightly high (7.40–7.45) but within the normal range. Pregnant women are predisposed to starvation ketosis as compared to nonpregnant states due to relative insulin resistance and increased production of the counter-regulatory hormone. Physiological mild hyponatremia occurs during pregnancy due to increased AVP secretion caused by resetting of osmoreceptors in the hypothalamus at a lower osmolality, but values below 130 mEq/L require a diagnostic workup and intervention. Gestational diabetes insipidus can occur due to increased production or decreased destruction of enzyme vasopressinase. Secretion of parathyroid hormone-related peptide by the placenta and breasts and two- to three-fold increased calcium and phosphate absorption in the maternal gut are the key changes in calcium metabolism during pregnancy. Though rare, both hypo- and hypercalcemia in pregnancy are associated with significant maternofetal morbidity and mortality.

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  1. Hankins GD, Clark SL, Harvey CJ, Uckan EM, Cotton D, Van Hook JW. Third-trimester arterial blood gas and acid base values in normal pregnancy at moderate altitude. Obstet Gynecol 1996;88(3):347–350. DOI: 10.1016/0029-7844(96)00210-4.
  2. LoMauro A, Aliverti A. Respiratory physiology of pregnancy: physiology masterclass. Breathe (Sheff) 2015;11(4):297–301. DOI: 10.1183/20734735.008615.
  3. Frise CJ, Mackillop L, Joash K, Williamson C. Starvation ketoacidosis in pregnancy. Eur J Obstet Gynecol Reprod Biol 2013;167(1):1–7. DOI: 10.1016/j.ejogrb.2012.10.005.
  4. Ekanem EI, Umoiyoho A, Inyang-Otu A. Study of electrolyte changes in patients with prolonged labour in ikot ekpene, a rural community in niger delta region of Nigeria. ISRN Obstet Gynecol 2012;2012:430265. DOI: 10.5402/2012/430265.
  5. Belzile M, Pouliot A, Cumyn A, Côté AM. Renal physiology and fluid and electrolyte disorders in pregnancy. Best Pract Res Clin Obstet Gynaecol 2019;57:1–14. DOI: 10.1016/j.bpobgyn.2018.11.008.
  6. Pazhayattil GS, Rastegar A, Brewster UC. Approach to the diagnosis and treatment of hyponatremia in pregnancy. Am J Kidney Dis 2015;65(4):623–627. DOI: 10.1053/j.ajkd.2014.09.027.
  7. Ananthakrishnan S. Gestational diabetes insipidus: diagnosis and management. Best Pract Res Clin Endocrinol Metab 2020;34(5):101384. DOI: 10.1016/j.beem.2020.101384.
  8. Jahnen-Dechent W, Ketteler M. Magnesium basics. Clin Kidney J 2012;5(Suppl. 1):i3–i14. DOI: 10.1093/ndtplus/sfr163.
  9. Dalton LM, Ní Fhloinn DM, Gaydadzhieva GT, Mazurkiewicz OM, Leeson H, Wright CP. Magnesium in pregnancy. Nutr Rev 2016;74(9):549–557. DOI: 10.1093/nutrit/nuw018.
  10. McCarthy FP, Magee CN, Plant WD, Kenny LC. Gitelman's syndrome in pregnancy: case report and review of the literature. Nephrol Dial Transplant 2010;25(4):1338–1340. DOI: 10.1093/ndt/gfp688.
  11. Ali DS, Dandurand K, Khan AA. Hypoparathyroidism in pregnancy and lactation: current approach to diagnosis and management. J Clin Med 2021;10(7):1378. DOI: 10.3390/jcm10071378.
  12. Almaghamsi A, Almalki MH, Buhary BM. Hypocalcemia in pregnancy: a clinical review update. Oman Med J 2018;33(6):453–462. DOI: 10.5001/omj.2018.85.
  13. Lai NK, Martinez D. Physiological roles of parathyroid hormone-related protein. Acta Biomed 2019;90(4):510–516. DOI: 10.23750/abm.v90i4.7715.
  14. Kumar A, Agarwal K, Devi SG, Gupta RK, Batra S. Hypocalcemia in pregnant women. Biol Trace Elem Res 2010;136(1):26–32. DOI: 10.1007/s12011-009-8523-6.
  15. Rey E, Jacob CE, Koolian M, Morin F. Hypercalcemia in pregnancy – a multifaceted challenge: case reports and literature review. Clin Case Rep 2016;4(10):1001–1008. DOI: 10.1002/ccr3.646.
  16. Appelman-Dijkstra NM, Ertl DA, Carola Zillikens M, Rjenmark L, Winter EM. Hypercalcemia during pregnancy: management and outcomes for mother and child. Endocrine 2021;71(3):604–610. DOI: 10.1007/s12020-021-02615-2.
  17. Mehanna HM, Moledina J, Travis J. Refeeding syndrome: what it is, and how to prevent and treat it. BMJ 2008;336(7659):1495–1498. DOI: 10.1136/bmj.a301.
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