Diagnostic Criteria for Hypertension in Pregnancy

Classification of Hypertensive Disorders

The European Society of Cardiology defines pre-existing (chronic) hypertension as hypertension (≥140/90 mmHg) that either predates pregnancy or develops before 20 weeks of gestation 1
The American Heart Association states that gestational hypertension is characterized by new-onset hypertension (≥140/90 mmHg) that develops at or after 20 weeks' gestation 2
The European Society of Cardiology notes that pre-eclampsia is a systemic disorder with both maternal and fetal manifestations, and is defined as gestational hypertension with significant proteinuria (≥0.3 g/day in 24h urine collection or ≥30 mg/mmol urinary creatinine in a spot sample) 1
The American College of Obstetricians and Gynecologists recommends that hypertensive disorders in pregnancy be classified into four main categories: pre-existing hypertension, gestational hypertension, pre-eclampsia, and pre-existing hypertension with superimposed gestational hypertension and proteinuria 2

The European Society of Hypertension recommends that diagnosis should be based on at least two high BP readings on two separate occasions 3
The American Heart Association states that for severe hypertension (≥160/110 mmHg), confirmation should be done within 15 minutes 2
The European Society of Cardiology notes that 24-hour ambulatory BP monitoring is superior to conventional measurements for predicting outcomes and may be useful for diagnosis, particularly in high-risk pregnant women 3

The American College of Obstetricians and Gynecologists recommends that proteinuria should be initially assessed by automated dipstick urinalysis when possible 2
The European Society of Cardiology defines significant proteinuria as ≥0.3 g/day in a 24h urine collection or ≥30 mg/mmol urinary creatinine in a spot random urine sample 1

The European Society of Cardiology notes that hypertensive disorders in pregnancy remain a major cause of maternal, fetal, and neonatal morbidity and mortality 1
The American Heart Association states that women with hypertension in pregnancy are at higher risk for severe complications including abruptio placentae, cerebrovascular accidents, organ failure, and disseminated intravascular coagulation 1

The American College of Cardiology and other major international guidelines define hypertension in pregnancy as blood pressure ≥140/90 mmHg measured on two separate occasions, regardless of whether it represents chronic hypertension, gestational hypertension, or preeclampsia 4, 5, 6, 7
This threshold applies to systolic BP ≥140 mmHg OR diastolic BP ≥90 mmHg, according to the European Heart Journal and Hypertension guidelines 4, 5

The European Heart Journal guidelines classify mild to moderate hypertension as 140-159/90-109 mmHg 5, 6, 7
Severe hypertension is defined as ≥160/110 mmHg, requiring urgent treatment within 15 minutes to prevent maternal stroke and other complications, according to the European Heart Journal and Stroke guidelines 5, 6, 7, 8

The 140/90 mmHg threshold applies uniformly across all hypertensive disorders of pregnancy, including chronic hypertension, gestational hypertension, preeclampsia, and superimposed preeclampsia, as stated by the European Heart Journal and Hypertension guidelines 4, 6, 7
Preeclampsia is defined as gestational hypertension with proteinuria or end-organ dysfunction, according to the European Heart Journal 7
Superimposed preeclampsia is defined as preeclampsia developing in women with chronic hypertension, according to the Stroke guidelines 5

Confirmation with home BP monitoring or 24-hour ambulatory BP monitoring is recommended before diagnosing true hypertension, as up to 25% of patients with elevated clinic readings have white-coat hypertension, according to the Hypertension guidelines 4
For home monitoring, the threshold is ≥135/85 mmHg, and for women before 22 weeks gestation, normal 24-hour ambulatory values should be below 126/76 mmHg (24-hour average), 132/79 mmHg (awake), and 114/66 mmHg (sleep), as stated by the Hypertension guidelines 4