Blood Pressure Threshold Defining Elevated Blood Pressure in Pregnancy
The correct answer is c. 140/90 mmHg, which defines hypertension in pregnancy according to all major international guidelines.
Diagnostic Threshold
Hypertension in pregnancy is uniformly defined as systolic BP ≥140 mmHg and/or diastolic BP ≥90 mmHg, measured on at least two separate occasions. 1, 2 This threshold applies regardless of whether the hypertension is chronic (pre-existing), gestational, or preeclampsia. 2
- The International Society for the Study of Hypertension in Pregnancy (ISSHP) explicitly states that hypertension is defined as systolic BP ≥140 and/or diastolic BP ≥90 mmHg. 1
- The European Society of Cardiology and European Society of Hypertension both confirm this same 140/90 mmHg threshold, noting that diagnosis should be based on absolute blood pressure values rather than changes from baseline. 1
- This definition has remained consistent despite the 2017 American College of Cardiology/American Heart Association lowering the threshold for hypertension in the general population, as pregnancy-specific guidelines continue to use 140/90 mmHg. 3
Why the Other Options Are Incorrect
- Option a (150/100 mmHg): This exceeds the diagnostic threshold and would miss many women with hypertension requiring monitoring and potential treatment. 1
- Option b (130/80 mmHg): While this defines stage 1 hypertension in non-pregnant adults per 2017 ACC/AHA guidelines, it is not the threshold used for pregnancy. 3
- Option d (160/110 mmHg): This defines severe hypertension requiring urgent treatment within 15 minutes, not the basic threshold for elevated blood pressure. 1, 2
Clinical Context and Severity Classification
Severe hypertension is separately defined as systolic BP ≥160 mmHg and/or diastolic BP ≥110 mmHg, which constitutes a hypertensive emergency requiring immediate intervention. 1, 2
- For severe hypertension, BP should be confirmed within 15 minutes and treatment initiated urgently to prevent maternal stroke and other complications. 1, 2
- For non-severe hypertension (140-159/90-109 mmHg), repeated readings should be taken over a few hours to confirm the diagnosis. 1
Important Measurement Considerations
- Use a liquid crystal sphygmomanometer if available, or a validated automated device that has been specifically tested in pregnancy and preeclampsia. 1
- Korotkoff phase V (disappearance of sound) should be used for diastolic BP measurement, not phase IV. 1
- 24-hour ambulatory BP monitoring is superior to office measurements for predicting pregnancy outcomes and may be particularly useful in high-risk women. 1, 2