What blood pressure parameter defines an elevated blood pressure in pregnant women?

Blood Pressure Threshold Defining Elevated Blood Pressure in Pregnancy

The correct answer is C: 140/90 mmHg defines elevated blood pressure in pregnancy. This threshold is consistently used across all major international guidelines to diagnose hypertension in pregnant women.

Diagnostic Threshold

Blood pressure ≥140/90 mmHg measured on two separate occasions defines hypertension in pregnancy, regardless of whether it represents chronic hypertension, gestational hypertension, or preeclampsia 1, 2.

• This threshold applies to systolic BP ≥140 mmHg OR diastolic BP ≥90 mmHg 1
• The diagnosis requires confirmation with at least two elevated readings on separate occasions 2, 3
• This definition differs from the 2017 ACC/AHA guidelines for non-pregnant adults, which lowered the threshold to 130/80 mmHg 4

Severity Classification

Once hypertension is diagnosed at ≥140/90 mmHg, it is further classified by severity:

• Mild to moderate hypertension: 140-159/90-109 mmHg 1
• Severe hypertension: ≥160/110 mmHg 1

Severe hypertension (≥160/110 mmHg) represents a hypertensive emergency requiring urgent treatment within 15 minutes to prevent maternal stroke and other complications 1, 5.

Why Other Options Are Incorrect

• 150/100 mmHg (option A): This exceeds the diagnostic threshold and represents moderate-to-severe hypertension requiring immediate treatment 1
• 130/80 mmHg (option B): While this defines stage 1 hypertension in non-pregnant adults per 2017 ACC/AHA guidelines, it is NOT the threshold used for pregnancy 4
• 160/110 mmHg (option D): This defines severe hypertension requiring emergency treatment, not the basic threshold for elevated BP 1

Clinical Application

The 140/90 mmHg threshold applies uniformly across all hypertensive disorders of pregnancy, including 1, 2:

• Chronic (pre-existing) hypertension: diagnosed before pregnancy or before 20 weeks gestation
• Gestational hypertension: new-onset hypertension after 20 weeks without proteinuria
• Preeclampsia: gestational hypertension with proteinuria or end-organ dysfunction
• Superimposed preeclampsia: preeclampsia developing in women with chronic hypertension

Important Caveats

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 1, 5. For home monitoring, the threshold is ≥135/85 mmHg 1, 5.

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) 1, 5.