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Definition of Gestation/Pregnancy-Induced Hypertension

1. Any new onset (not previously diagnosed) of hypertension (SBP > 140mmHg and/or DBP > 90mmHg) at > 20 weeks gestation in the absence of proteinuria or new signs of end-organ damage
   1. Severe = SBP > 160mmHg and/or DBP > 110mmHg
2. Documented on at least 2 occasions at least 4 hours apart

Epidemiology

• 5-10% of all pregnancies
  • 6-17% of healthy nulliparous women
  • 2-4% of healthy multiparous women
• 16% of all maternal deaths are related to hypertensive disorders

Pathophysiology

This is still unknown but several theories exist and include:

• Maladaption to the normal physiologic changes of pregnancy
  • Increased blood volume
  • Elevated angiotensinogen from increased estrogen production
• Abnormal trophoblast invasion of uterine blood vessels
  • Causes spiral arterioles to narrow
• Immunologic intolerance between fetoplacental and maternal tissues

Risk Factors

• Previous history of preeclampsia
• Multifetal gestation
• Overweight/obese
• African-American

Fetal Well-being

• Non-stress test and ultrasound should be performed upon diagnosis to assess fetal growth, fetal measurements, and amniotic fluid estimation and serially depending on severity.

Laboratory Evaluation

• 24-hour urine collection for protein
  • > 300mg of protein = proteinuria
• Platelet count
  • < 100,000 = thrombocytopenia
• Liver Function Test
  • 2x transaminases = impaired liver function
• Serum creatinine
  • > 1.1mg/dL = impaired renal function

Preeclampsia

• Gestational hypertension with proteinuria and/or end-organ damage
  • Pulmonary edema, cerebral or visual disturbance, or any of the above laboratory abnormalities
• 10-50% of women with gestation hypertension go on to develop preeclampsia within 5 weeks of diagnosis
• Risk factors
  • Gestational hypertension diagnosed < 34 weeks gestation
  • Mean SBP > 135mmHg on 24-hour monitoring
  • Abnormal uterine artery Doppler
  • Elevated serum uric acid level (> 5.2mg/dL)

Management

Revolves around 3 main factors:

1. Fetal growth and maturation
2. Maternal and fetal benefits from early intervention
3. Maternal and fetal risk from expectant management

HYPITAT-II Trial (HYPertension and Preeclampsia Intervention At Term)

• 897 women diagnosed with non-severe gestational hypertension between 34-37 weeks gestation
• Study group – delivery within 24-hours of diagnosis (induction or cesarean)
• Control group – management until 37 weeks gestation
• Results
  • 3% of control group vs 0% of study group developed at least one of the following:
    • Thromboembolic complications
    • HELLP syndrome
    • Eclampsia
    • Placental abruption
  • 3% of of study group developed neonatal respiratory distress syndrome vs 1.1% of control group

Non-severe (<160/110mmHg) and no preeclampsia

• Screening
  • BP monitoring one or twice weekly with weekly assessment of proteinuria, platelet count, and liver enzymes
  • Weekly NST with sonographic estimation of amniotic fluid index
• No evidence for starting antihypertensive therapy, unless patient has pre-existing end-organ dysfunction that could be worsened with hypertension (renal, cardiac, etc.)
• Plan for delivery between 37-38 weeks

Severe (>160/110mmHg) and no preeclampsia

• Same screening recommendations
• Should be treated with antihypertensive therapy

• Goals
  • No evidence of end-organ damage = < 160/110mmHg
  • Evidence of end-organ damage = < 140/90mmHg

• Corticosteroids
  • Antenatal corticosteroids (23-34 weeks gestation) significantly reduces the risk of respiratory distress syndrome, intraventricular hemorrhage, and neonatal death
  • Promotes fetal lung maturity
    • Increases lecithin:sphingomyelin ratio
    • Accelerates development of type 1 and type II pneumocytes
      • Increases surfactant levels
    • Dosing
      • Betamethasone 12mg x 2 IM given 24 hours apart
      • Dexamethasone 6mg x 4 IM given 12 hours apart
    • Plan for delivery
      • Delivery between 34-36 weeks, unless preeclampsia develops

Preeclampsia

• Severe preeclampsia is gestation hypertension with proteinuria AND one of the following:
  • Symptoms of CNS dysfunction
    • Photopsia, scotomata, cortical blindness, retinal vasospasm
    • Severe headache
    • AMS
  • Hepatic abnormality
    • RUQ pain or transaminases > 2x normal
  • SBP > 160mmHg or DBP > 110mmHg
  • Thrombocytopenia (<100k)
  • Renal abnormality (creatinine > 1.1mg/dL)
  • Pulmonary edema

• Complications

• Management of severe disease
  • If > 34 weeks, immediate delivery
  • If > 24 weeks but < 34 weeks, hospitalize until delivery and consult high-risk maternal/fetal specialist for management and delivery decision based on risk/benefit
    • BP checks every 4 hours
    • Daily NST, twice weekly ultrasound for measurements, weekly umbilical artery doppler
    • Strict I&Os
    • CBC, creatinine, LFT twice weekly
    • Corticosteroids (if not already given)
  • If < 24 weeks, consider termination of pregnancy
    • < 20% fetal survival
• Management of non-severe disease
  • Inpatient vs outpatient = no difference in outcomes
  • Bedrest
  • Office follow-up every 1-3 days
  • Weekly platelet count, creatinine, and LFTs
  • Delivery at 34-36 weeks
• Intrapartum management
  • BP control
  • Seizure prophylaxis
    • Magnesium sulfate
      • 6g IV over 20min, followed by 2g/hr as infusion
      • Continued for 24 hours post-partum

Long-term Prognosis

• 15% of women with gestational hypertension have persistent hypertension after 12 weeks post-partum
• 22% of women will develop gestation hypertension again with subsequent pregnancies
• Increased risk of cardiovascular disease, hyperlipidemia, kidney disease, and diabetes

 

References

1) ACOG Task Force on Hypertension in Pregnancy.  Obstetrics & Gynecology.  2013;122(5).

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

3) Yoder SR, Thornburg LL, Bisognano JD. Hypertension in pregnancy and women of childbearing age. Am J Med. 2009;122(10):890-5.

4) Gaillard R, Steegers EA, Hofman A, Jaddoe VW. Associations of maternal obesity with blood pressure and the risks of gestational hypertensive disorders. The Generation R Study. J Hypertens. 2011;29(5):937-44.

5) Sibai BM. Diagnosis and management of gestational hypertension and preeclampsia. Obstet Gynecol. 2003;102(1):181-92.

6) Khan KS, Wojdyla D, Say L, Gülmezoglu AM, Van look PF. WHO analysis of causes of maternal death: a systematic review. Lancet. 2006;367(9516):1066-74.

7) Saudan P, Brown MA, Buddle ML, Jones M. Does gestational hypertension become pre-eclampsia?. Br J Obstet Gynaecol. 1998;105(11):1177-84.

8) Melamed N, Ray JG, Hladunewich M, Cox B, Kingdom JC. Gestational hypertension and preeclampsia: are they the same disease?. J Obstet Gynaecol Can. 2014;36(7):642-7.

9) Wu Y, Xiong X, Fraser WD, Luo ZC. Association of uric acid with progression to preeclampsia and development of adverse conditions in gestational hypertensive pregnancies. Am J Hypertens. 2012;25(6):711-7.

10) Broekhuijsen K, Van baaren GJ, Van pampus MG, et al. Immediate delivery versus expectant monitoring for hypertensive disorders of pregnancy between 34 and 37 weeks of gestation (HYPITAT-II): an open-label, randomised controlled trial. Lancet. 2015;385(9986):2492-501.

11) Spong CY, Mercer BM, D’alton M, Kilpatrick S, Blackwell S, Saade G. Timing of indicated late-preterm and early-term birth. Obstet Gynecol. 2011;118(2 Pt 1):323-33.

12) Roberts D, Dalziel S. Antenatal corticosteroids for accelerating fetal lung maturation for women at risk of preterm birth. Cochrane Database Syst Rev. 2006;(3):CD004454.

13) Carlo WA, Mcdonald SA, Fanaroff AA, et al. Association of antenatal corticosteroids with mortality and neurodevelopmental outcomes among infants born at 22 to 25 weeks’ gestation. JAMA. 2011;306(21):2348-58.

14) Bombrys AE, Barton JR, Nowacki EA, et al. Expectant management of severe preeclampsia at less than 27 weeks’ gestation: maternal and perinatal outcomes according to gestational age by weeks at onset of expectant management. Am J Obstet Gynecol. 2008;199(3):247.e1-6.

15) Sibai BM. Magnesium sulfate prophylaxis in preeclampsia: Lessons learned from recent trials. Am J Obstet Gynecol. 2004;190(6):1520-6.

16) Reiter L, Brown MA, Whitworth JA. Hypertension in pregnancy: the incidence of underlying renal disease and essential hypertension. Am J Kidney Dis. 1994;24(6):883-7.

17) Van oostwaard MF, Langenveld J, Schuit E, et al. Recurrence of hypertensive disorders of pregnancy: an individual patient data metaanalysis. Am J Obstet Gynecol. 2015;212(5):624.e1-17.

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