Hypertensive disorders of pregnancy: ISSHP 2021 classification and chronic hypertension

It is the Tuesday antenatal clinic and the midwife hands you a card: 148/94 mmHg at 26 weeks, first pregnancy, no earlier reading because she booked late. Is this chronic hypertension unmasking, gestational hypertension declaring itself, or preeclampsia already under way? The answer changes everything you do next — and the examiner will ask you to justify each fork.^[1][18]

Overview and definition

Hypertension in pregnancy is a systolic pressure of 140 mmHg or more and/or a diastolic of 90 mmHg or more, measured properly, on at least two occasions at least four hours apart — or once if the reading is in the severe range.^[1][3]

• Severe range is 160/110 mmHg or more. That is an emergency threshold, not a diagnostic category; one confirmed reading commits you to treatment.^[1][4]
• Diastolic uses Korotkoff phase V (disappearance of sounds), not muffling. Phase IV was abandoned because it is less reproducible.^[2][3]
• The measurement is the diagnosis. A wrong cuff or an unrested patient manufactures a hypertensive disorder that then drives induction. Get this right before you get anything else right.^[1][3]

^{[3] [4] [7]}

References20ShowHide

1. [1]Magee LA, Brown MA, Hall DR, et al. The 2021 International Society for the Study of Hypertension in Pregnancy classification, diagnosis & management recommendations for international practice Pregnancy Hypertens, 2022.PMID 35066406
2. [2]Brown MA, Magee LA, Kenny LC, et al. Hypertensive Disorders of Pregnancy: ISSHP Classification, Diagnosis, and Management Recommendations for International Practice Hypertension, 2018.PMID 29899139
3. [3]Shanmugalingam R, Barrett HL, Beech A, et al. A summary of the 2023 Society of Obstetric Medicine of Australia and New Zealand (SOMANZ) hypertension in pregnancy guideline Med J Aust, 2024.PMID 38763516
4. [4]American College of Obstetricians and Gynecologists Gestational Hypertension and Preeclampsia: ACOG Practice Bulletin, Number 222 Obstet Gynecol, 2020.PMID 32443079
5. [5]American College of Obstetricians and Gynecologists' Committee on Practice Bulletins—Obstetrics ACOG Practice Bulletin No. 203: Chronic Hypertension in Pregnancy Obstet Gynecol, 2019.PMID 30575676
6. [6]Magee LA, von Dadelszen P, Rey E, et al. Less-tight versus tight control of hypertension in pregnancy N Engl J Med, 2015.PMID 25629739
7. [7]Tita AT, Szychowski JM, Boggess K, et al. Treatment for Mild Chronic Hypertension during Pregnancy N Engl J Med, 2022.PMID 35363951
8. [8]Abalos E, Duley L, Steyn DW, Gialdini C Antihypertensive drug therapy for mild to moderate hypertension during pregnancy Cochrane Database Syst Rev, 2018.PMID 30277556
9. [9]Duley L, Meher S, Jones L Drugs for treatment of very high blood pressure during pregnancy Cochrane Database Syst Rev, 2013.PMID 23900968
10. [10]Easterling T, Mundle S, Bracken H, et al. Oral antihypertensive regimens (nifedipine retard, labetalol, and methyldopa) for management of severe hypertension in pregnancy: an open-label, randomised controlled trial Lancet, 2019.PMID 31378394
11. [11]Magee LA, Cham C, Waterman EJ, Ohlsson A, von Dadelszen P Hydralazine for treatment of severe hypertension in pregnancy: meta-analysis BMJ, 2003.PMID 14576246
12. [12]Shekhar S, Gupta N, Kirubakaran R, Pareek P Oral nifedipine versus intravenous labetalol for severe hypertension during pregnancy: a systematic review and meta-analysis BJOG, 2016.PMID 26113232
13. [13]Tucker KL, Mort S, Yu LM, et al. Effect of Self-monitoring of Blood Pressure on Diagnosis of Hypertension During Higher-Risk Pregnancy: The BUMP 1 Randomized Clinical Trial JAMA, 2022.PMID 35503346
14. [14]Rolnik DL, Wright D, Poon LC, et al. Aspirin versus Placebo in Pregnancies at High Risk for Preterm Preeclampsia N Engl J Med, 2017.PMID 28657417
15. [15]Bellamy L, Casas JP, Hingorani AD, Williams DJ Pre-eclampsia and risk of cardiovascular disease and cancer in later life: systematic review and meta-analysis BMJ, 2007.PMID 17975258
16. [16]Wu P, Haththotuwa R, Kwok CS, et al. Preeclampsia and Future Cardiovascular Health: A Systematic Review and Meta-Analysis Circ Cardiovasc Qual Outcomes, 2017.PMID 28228456
17. [17]Brouwers L, van der Meiden-van Roest AJ, Savelkoul C, et al. Recurrence of pre-eclampsia and the risk of future hypertension and cardiovascular disease: a systematic review and meta-analysis BJOG, 2018.PMID 29978553
18. [18]Magee LA, Nicolaides KH, von Dadelszen P Preeclampsia N Engl J Med, 2022.PMID 35544388
19. [19]Burton GJ, Redman CW, Roberts JM, Moffett A Pre-eclampsia: pathophysiology and clinical implications BMJ, 2019.PMID 31307997
20. [20]Sibai BM Etiology and management of postpartum hypertension-preeclampsia Am J Obstet Gynecol, 2012.PMID 21963308