Clinical Review

Pregnancy-Induced Hypertension

Clinician Reviews. 2012 May;22(5):27-32

Author(s):

Women with pregnancy-induced hypertension (PIH) are at increased risk for preeclampsia, cesarean delivery, renal dysfunction, and placental abruption; associated risks to the fetus include intrauterine growth restriction, preterm delivery, low birth weight, and neonatal ICU admission. Ongoing monitoring for increased hypertension and proteinuria, consideration of expectant management or labor induction, and appropriate use of antihypertensive therapy are essential components in the management of women with PIH.

PDF Download

References

1. Report of the National High Blood Pressure Education Program Working Group on high blood pressure in pregnancy. Am J Obstet Gynecol. 2000;183(1):S1-S22.

2. Sibai BM. Diagnosis and management of gestational hypertension and preeclampsia. Obstet Gynecol. 2003;102(1):181-192.

3. Kuklina EV, Ayala C, Callaghan WM. Hypertensive disorders and severe obstetric morbidity in the United States. Obstet Gynecol. 2009; 113(6):1299-1306.

4. Villar J, Carroli, G, Wojdyla D, et al; World Health Organization Antenatal Care Trial Research Group. Preeclampsia, gestational hypertension and intrauterine growth restriction, related or independent conditions. Am J Obstet Gynecol. 2006;194(4):921-931.

5. Leeman L, Fontaine P. Hypertensive disorders of pregnancy. Am Fam Physician. 2008;78(1):
93-100.

6. Magee LA, Helewa M, Moutquin JM, von Dadelszen P; Hypertension Guideline Committee; Strategic Training Initiative in Research in the Reproductive Health Sciences (STIRRHS) Scholars. Diagnosis, evaluation, and management of the hypertensive disorders of pregnancy. J Obstet Gynaecol Can. 2008;30(3 suppl):S1-S48.

7. Buchbinder A, Sibai BM, Caritis S, et al. Adverse perinatal outcomes are significantly higher in severe gestational hypertension than in mild preeclampsia. Am J Obstet Gynecol. 2002;186(1):66-71.

8. Hauth JC, Ewell MG, Levine RJ, et al; Calcium for Preeclampsia Prevention Study Group. Pregnancy outcomes in healthy nulliparas who developed hypertension. Obstet Gynecol. 2000;95(1):24-28.

9. Magnussen EB, Vatten LJ, Smith GD, Romundstad PR. Hypertensive disorders in pregnancy and subsequently measured cardiovascular risk factors. Obstet Gynecol. 2009; 114(5):961-970.

10. Lindheimer MD, Taler SJ, Cunningham FG; American Society of Hypertension (ASH). ASH position paper: hypertension in pregnancy. J Clin Hypertens (Greenwich). 2009;11(4):214-225.

11. Roberts JM, Gammill HS. Preeclampsia: recent insights. Hypertension. 2005;46(6):
1243-1249.

12. Saudan P, Brown MA, Buddle ML, Jones M. Does gestational hypertension become pre-eclampsia? Br J Obstet Gynaecol. 1998;105 (11):1177-1184.

13. Visintin C, Mugglestone MA, Almerie MQ, et al; Guideline Development Group. Management of hypertensive disorders during pregnancy: summary of NICE guidance. BMJ. 2010;341:c2207.

14. ACOG Committee on Practice Bulletins—Obstetrics. Clinical Management Guidelines for Obstetrician–Gynecologists. Diagnosis and management of preeclampsia and eclampsia: ACOG practice bulletin No. 33. Obstet Gynecol. 2002;99:159-167.

15. Parazzini F, Bortolus R, Chatenoud L, et al; Italian Study of Aspirin in Pregnancy Group. Risk factors for pregnancy-induced hypertension in women at high risk for the condition. Epidemiology. 1996;7(3):306-308.

16. Hjartardottir S, Leifsson BG, Geirsson RT, Steinthorsdottir V. Recurrence of hypertensive disorder in second pregnancy. Am J Obstet Gynecol. 2006;194(4):916-920.

17. Barton JR, O’Brien JM, Bergauer NK, et al. Mild gestational hypertension remote from term: progression and outcome. Am J Obstet Gynecol. 2001;184(5):979-983.

18. Brown MA, Mackenzie C, Dunsmuir W, et al. Can we predict recurrence of pre-eclampsia or gestational hypertension? BJOG. 2007; 114(8):984-993.

19. Bellomo G, Venanzi S, Saronio P, et al. Prognostic significance of serum uric acid in women with gestational hypertension. Hypertension. 2011;58(4):704-708.

20. Hawkins TL, Roberts JM, Mangos GJ, et al. Plasma uric acid remains a marker of poor outcome in hypertensive pregnancy: a retrospective cohort study. BJOG. 2012;119(4):484-492.

21. National Institute for Health and Clinical Excellence. Hypertension in pregnancy: the management of hypertensive disorders during pregnancy. www.nice.org.uk/nicemedia/live/13098/50418/50418.pdf. Accessed April 16, 2012.

22. Koopmans CM, Bijlenga D, Groen H, et al. Induction of labour versus expectant monitoring for gestational hypertension or mild pre-eclampsia after 36 weeks’ gestation (HYPITAT): a multicentre, open-label randomised controlled trial. Lancet. 2009;374(9694):979-988.

23. Caughey AB, Sundaram V, Kaimal AJ, et al. Maternal and neonatal outcomes of elective induction of labor. Evid Rep Technol Assess (Full Rep). 2009;(176):1-257.

24. Shennan A, Hezelgrave N. An economic analysis of induction of labour and expectant monitoring in women with gestational hypertension or pre-eclampsia at term (HYPITAT trial). BJOG. 2010;117(13):1575-1576.

25. Abalos E, Duley L, Steyn DW, Henderson-Smart DJ. Antihypertensive drug therapy for mild to moderate hypertension during pregnancy. Cochrane Database Syst Rev. 2007 Jan 24;(1):CD002252.

26. Nabhan AF, Elsedawy MM. Tight control of mild-moderate pre-existing or non-proteinuric gestational hypertension. Cochrane Database Syst Rev. 2011 Jul 6;(7):CD006907.

27. Duley L, Gülmezoglu AM, Henderson-Smart DJ. Magnesium sulphate and other anticonvulsants for women with preeclampsia. Cochrane Database Syst Rev. 2003;(2):CD000025.

28. Kraft MD, Btaiche IF, Sacks GS, Kudsk KA. Treatment of electrolyte disorders in adult patients in the intensive care unit. Am J Health Syst Pharm. 2005;62(16):1663-1682.

29. FamilyDoctor.org. Pregnancy-induced hypertension (updated 2010). http://familydoctor.org/familydoctor/en/diseases-conditions/pregnancy-induced-hypertension.printerview
.all.html. Accessed April 16, 2012.

30. Zamorski MA, Green LA. NHBPEP report on high blood pressure in pregnancy: a summary for family physicians. Am Fam Physician. 2001; 64(2):263-270.

31. Hofmeyr GJ, Duley L, Atallah A. Dietary calcium supplementation for prevention of pre-eclampsia and related problems: a systematic review and commentary. BJOG. 2007;114(8): 933-943.

32. Ferrazzani S, De Carolis S, Pomini F, et al. The duration of hypertension in the puerperium of preeclamptic women: relationship with renal impairment and week of delivery. Am J Obstet Gynecol. 1994;171(2):506-512.

33. Beardmore KS, Morris JM, Gallery ED. Excretion of antihypertensive medication into human breast milk: a systematic review. Hypertens Pregnancy. 2002;21(1):85-95.

34. Wilson BJ, Watson MS, Prescott GJ, et al. Hypertensive diseases of pregnancy and risk of hypertension and stroke in later life: results from cohort study. BMJ. 2003;326(7394):845.

Hypertensive disorders represent one of the most common medical complications of pregnancy.^1,2 Based on a nationwide inpatient sample examining more than 36 million deliveries in the United States, the prevalence of associated hypertensive disorders increased from 67.2 per 1,000 deliveries in 1998 to 83.4 per 1,000 deliveries in 2006.³Pregnancy-induced hypertension (also referred to as gestational hypertension or hypertensive disorder of pregnancy)^4-6 is estimated to affect 6% to 8% of US pregnancies.^1,2

Women who develop severe hypertension during pregnancy may experience adverse effects similar to those associated with mild preeclampsia.^2,7,8 In the mother, these may range from elevated liver enzymes to renal dysfunction; and in the fetus, from preterm delivery to intrauterine restriction of fetal growth.^7,8

This article will review the risk factors, clinical presentation, diagnosis, and management of pregnancy-induced hypertension. A brief discussion of preeclampsia as it relates to gestational hypertension will be included (see Table 1^2,6,9).

Classification, Definitions

Pregnancy-induced hypertension (PIH) is classified as mild or severe. Mild PIH is defined as new-onset hypertension (systolic blood pressure ≥ 140 mm Hg and/or diastolic blood pressure ≥ 90 mm Hg), occurring after 20 weeks’ gestation. The majority of cases of mild PIH develop beyond 37 weeks’ gestation, and in these cases, pregnancy outcomes are comparable to those of normotensive pregnancies.^2,7,8

Severe PIH is defined as sustained elevated blood pressures of ≥ 160 mm Hg systolic and ≥ 110 mm Hg diastolic. In prospective cohort studies in which calcium supplementation and low-dose aspirin use were being investigated for prevention of preeclampsia in healthy pregnant women, those who were severely hypertensive were found to be at increased risk for certain maternal comorbidities (eg, cesarean delivery, renal dysfunction, elevated liver enzymes, placental abruption) and perinatal morbidities (delivery before 37 weeks’ gestation, low birth weight, fetal growth restriction, and neonatal ICU admission), compared with patients who were normotensive or mildly hypertensive.^7,8

The diagnosis of PIH may later be amended or replaced by one of the following diagnoses: preeclampsia, if proteinuria (to be defined and discussed later) develops; chronic hypertension, if blood pressure remains elevated past 12 weeks postpartum; or transient hypertension of pregnancy, if blood pressure normalizes by 12 weeks postpartum.^5,6,10

Pathophysiology and Risk Factors

Although the pathophysiology of PIH is not well understood, the pathogenesis of preeclampsia likely involves abnormalities in the development, implantation, or perfusion of the placenta, and often leads to impaired maternal organ function.^6,11 It is not clear whether PIH and preeclampsia are two different diseases that share a manifestation of elevated blood pressure or whether PIH represents an early stage of preeclampsia.^4,12 However, women with preexisting hypertension, especially severe hypertension, are at increased risk for preeclampsia, placental abruption, and fetal growth restriction.²

There are some similarities and some distinct differences among the clinical features and risk factors associated with PIH, compared with those of preeclampsia. Risk factors for PIH include a pre-pregnancy BMI of 25 or greater, PIH and/or preeclampsia in previous pregnancies, and history of renal disease, cardiac disease, or diabetes. The most important risk factors for preeclampsia include preexisting diabetes or nephropathy, chronic hypertension, PIH or preeclampsia in a previous pregnancy, maternal age younger than 18 or older than 34, African-American ethnicity, first pregnancy, multiple pregnancy, history of preeclampsia in the patient’s mother or sister, obesity, autoimmune disease, and an interval between pregnancies longer than 10 years.^4-6,13-15

The risk for preeclampsia in patients with PIH is approximately 15% to 25%^12,16; according to Magee et al,⁶ 35% of women with PIH onset before 37 weeks’ gestation develop preeclampsia.^6,12,17 The risk for recurrence of PIH in subsequent pregnancies is about 26%, whereas women who experience preeclampsia in one pregnancy have a comparable risk for PIH or preeclampsia (about 14% each) in subsequent pregnancies.¹⁸

Clinical Presentation and Diagnostic Evaluation

Blood pressure should be measured and recorded at every prenatal visit, using the correct-sized cuff, with the patient in a seated position.⁵ Gestational hypertension is a clinical diagnosis confirmed by at least two accurate blood pressure measurements in the same arm in women without proteinuria, with readings of ≥ 140 mm Hg systolic and/or ≥ 90 mm Hg diastolic. It should then be determined whether the patient’s hypertension is mild or severe (ie, blood pressure > 160/110 mm Hg). The patient with severe PIH should be evaluated for signs of preeclampsia, as discussed below.

Patients with mild PIH are often asymptomatic, and the diagnosis is made at a prenatal visit as a result of routine blood pressure monitoring; this is one of many reasons to encourage early and regular prenatal care. Blood pressure may be higher at night in hypertensive disorders of pregnancy.¹⁰