Hypertension in Pregnancy

Original Editor - Manisha Shrestha Top Contributors - Manisha Shrestha, Kirenga Bamurange Liliane, Nupur Smit Shah, Kim Jackson and Lucinda hampton

Original Editor - User Name

Top Contributors - Manisha Shrestha, Kirenga Bamurange Liliane, Nupur Smit Shah, Kim Jackson and Lucinda hampton  

Introduction

Hypertensive disorders of pregnancy is a leading cause of maternal and neonatal morbidity and mortality. Hypertension in pregnancy should be defined as a hospital systolic blood pressure (SBP) ⩾ 140 mmHg and/or dyiatolic blood pressure (DBP) ⩾ 90 mmHg, based on the average of at least two measurements, taken at least 15 min apart, using the same arm.

Classification

A. Pre- existing (chronic hypertension)

This is defined as hypertension that was present either pre-pregnancy or that develops at <20 weeks of gestation. A substantial number of pregnancies (0.2– 5%) are complicated by pre-existing hypertension and the prevalence in western societies is likely to increase due to the advancing age of the prospective mother at conception and the rising tide of obesity. Chronic hypertension of all causes can be divided into essential and secondary hypertension based upon its causes.

• With comorbid condition(s):

Comorbid conditions (e.g., pre-gestational type I or II diabetes mellitus or kidney disease) warrant tighter BP control outside of pregnancy because of their association with heightened cardiovascular risk.

• With evidence of preeclampsia:

This is also known as ‘superimposed preeclampsia’ and is defined by the development of one or more of the following at ⩾ 20 weeks:

• Resistant hypertension, or
• New or worsening proteinuria, or
• One/more adverse condition(s) or
• One/more severe complication(s)

B. Gestational hypertension

This is defined as hypertension that develops for the first time at ⩾ 20 weeks of gestation.

• With comorbid condition(s): Comorbid conditions (e.g., pregestational type I or II diabetes mellitus or kidney disease) warrant tighter BP control outside of pregnancy because of their association with heightened cardiovascular risk.

• With evidence of preeclampsia: Evidence of preeclampsia may appear many weeks after the onset of gestational hypertension.

C. Pre-eclampsia

Preeclampsia is defined by gestational hypertension and one or more of the following:

• New proteinuria, or
• One/more adverse conditions, or
• One/more severe complication(s)

Severe preeclampsia is defined as preeclampsia with one or more severe complication(s).

Preeclampsia results from a mismatch between uteroplacental supply and fetal demands, leading to its systemic inflammatory maternal (and fetal) manifestations. The risk of small at gestational age (SGA) infants is primarily among women who present at <34 weeks, with macrosomia more common with term preeclampsia.

D. Other hypertensive effects

• Transient hypertensive effect: Elevated BP may be due to environmental stimuli or the pain of labour. A transient hypertensive effect is not associated with an increased risk of adverse outcomes.
• White-coat hypertensive effect: BP that is elevated in the office i.e in the presence of a clinical attendant (sBP ⩾ 140 mmHg or dBP ⩾ 90 mmHg) but is consistently normal outside of the office (<135/85 mmHg) by ambulatory BP monitoring (ABPM) or home BP monitoring(HBPM). These women appear to have a lower risk of superimposed pre-eclampsia than women with true essential hypertension. White-coat effect in early pregnancy is common. Forty percent of women progress to persistent hypertension at ≥ 20 weeks (i.e., gestational hypertension) and 8% to pre-eclampsia. Women with white-coat effects have risks (e.g., severe hypertension, preterm delivery, and NICU admission) intermediate between normotension and either chronic or gestational hypertension.
• Masked hypertensive effect: BP that is consistently normal in the office (sBP < 140 mmHg or dBP < 90 mmHg) but is elevated outside of the office (⩾135/85 mmHg) by ABPM or repeated HBPM.

Adverse conditions and severe complications of preeclampsia.

Adverse conditions consist of maternal symptoms, signs, and abnormal laboratory results, and abnormal fetal monitoring results that may herald the development of severe maternal or fetal complications.

Organ system affected	Adverse conditions (that increase the risk of severe complications)	Severe complications (that warrant delivery)
CNS	Headache/visual symptoms	Eclampsia PRES Cortical blindness or retinal detachment Glasgow coma scale < 13 Stroke, TIA, or RIND
Cardiorespiratory	Chest pain/dyspnoea Oxygen saturation < 97%	Uncontrolled severe hypertension (over a period of 12hr despite use of three antihypertensive agents), Oxygen saturation < 90%, need for ⩾ 50% oxygen for > 1hr, intubation (other than for Caesarean section), pulmonary oedema Positive inotropic support Myocardial ischaemia or infarction
Haematological	Elevated WBC count Elevated INR or aPTT  Low platelet count	Platelet count < 50x109/L Transfusion of any blood product
Renal	Elevated serum creatinine  Elevated serum uric acid	Acute kidney injury (creatinine > 150 μM with no prior renal diseases New indication for dialysis
Hepatic	Nausea or vomiting RUQ or epigastric pain Elevated serum AST, ALT, LDH, or bilirubin Low plasma albumin	Hepatic dysfunction (INR > 2 in absence of DIC or warfarin) Hepatic haematoma or rupture
Feto-placental	Non-reassuring FHR IUGR  Oligohydramnios Absent or reversed end-diastolic flow by Doppler velocimetry	Non-reassuring FHR IUGR Oligohydramnios Absent or reversed end-diastolic flow by Doppler velocimetry

ST, aspartate aminotransferase; ALT, alanine aminotransferase; DIC, disseminated intravascular coagulation; FHR, fetal heart rate; LDH, lactate dehydrogenase; PRES, posterior reversible leukoencephalopathy syndrome; RIND, reversible neurological deficit < 48hr; RUQ, right upper quadrant; TIA, transient ischaemic attack.

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