The 2017 American College of Cardiology and American Heart Association blood pressure categories in the second half of pregnancy-a systematic review of their association with adverse pregnancy outcomes.

OBJECTIVE: A relationship between the 2017 American College of Cardiology and American Heart Association blood pressure thresholds and adverse pregnancy outcomes has been reported, but few studies have explored the diagnostic test properties of these cutoffs when used within pregnancy. DATA SOURCES: Electronic databases were searched (2017-2021) for measurements of blood pressure in pregnancy at >20 weeks, classified according to the 2017 American College of Cardiology and American Heart Association criteria, and their relationship with pregnancy outcomes. Blood pressure was categorized as "normal" (systolic blood pressure of <120 mm Hg and diastolic blood pressure of <80 mm Hg), "elevated blood pressure" (systolic blood pressure of 120-129 mm Hg and diastolic blood pressure of <80 mm Hg), "stage 1 hypertension" (systolic blood pressure of 130-139 mm Hg and/or diastolic blood pressure of 80-89 mm Hg), and "stage 2 hypertension" (systolic blood pressure of ≥140 mm Hg and/or diastolic blood pressure of ≥90 mm Hg). STUDY ELIGIBILITY CRITERIA: Studies recording blood pressure at or above 20 weeks gestation were included. METHODS: Meta-analyses were used to investigate the strength of the association between blood pressure cutoffs and adverse outcomes, and the diagnostic test properties were calculated accounting for gestation. RESULTS: There were 12 included studies. The American College of Cardiology or American Heart Association blood pressure categories were determined from peak blood pressures at any point from 20 weeks of gestation and at specific gestational ages (20-27, 28-32, or 33-36 weeks of gestation), as available. A higher (vs normal) blood pressure category was consistently associated with adverse outcomes. The strength of association between blood pressure categories and adverse outcomes was the greatest with "stage 2 hypertension" (blood pressure of ≥140/90 mm Hg). The results were similar when peak blood pressure was reported either at any time from 20 weeks of gestation or within gestational age groups (as above). No blood pressure category was useful as a diagnostic "rule-out test" for adverse outcomes, as all negative likelihood ratios were ≥0.2. Only "stage 2 hypertension" was useful as a "rule in-test," with positive likelihood ratios of ≥5.0, for maximum blood pressure at >20 weeks of gestation for preeclampsia and blood pressure within any gestational age groups for preeclampsia, eclampsia, stroke, maternal death, and stillbirth. CONCLUSION: From 20 weeks of gestation, blood pressure thresholds of 140 mm Hg (systolic) and 90 mm Hg (diastolic) were useful in identifying women at increased risk of adverse pregnancy outcomes, irrespective of the specific gestational age at blood pressure measurement. Lowering the blood pressure threshold for abnormal blood pressure at >20 weeks of gestation would not assist clinicians in identifying women at heightened maternal or perinatal risk. No American College of Cardiology or American Heart Association blood pressure threshold can provide reassurance that women are unlikely to develop adverse outcomes.

American College of Cardiology and American Heart Association blood pressure categories-a systematic review of the relationship with adverse pregnancy outcomes in the first half of pregnancy.

OBJECTIVE: A relationship between the 2017 American College of Cardiology and American Heart Association blood pressure thresholds and adverse pregnancy outcomes has been reported, but few studies have explored the diagnostic test properties of these cutoffs. DATA SOURCES: We systematically searched electronic databases (from 2017 to 2021) for reports of blood pressure measurements in pregnancy, classified according to 2017 American College of Cardiology and American Heart Association criteria, and their relationship with pregnancy outcomes. STUDY ELIGIBILITY CRITERIA: Studies recording blood pressure at <20 weeks gestation were included. METHODS: Meta-analyses were used to investigate the strength of the association between blood pressure cutoffs and adverse outcomes, and the diagnostic test properties were calculated. RESULTS: Of 23 studies included, there was a stepwise relationship between the American College of Cardiology and American Heart Association blood pressure category (when compared with normal blood pressure of <120/80 mmHg) and the strength of the association with preeclampsia. The category of elevated blood pressure had a risk ratio of 2.0 (95% prediction interval, 0.8-4.8), the stage 1 hypertension category had a risk ratio of 3.0 (95% prediction interval, 1.1-8.5), and the stage 2 hypertension category had a risk ratio of 7.9 (95% prediction interval, 1.8-35.1). Between-study variability was related to the magnitude of the association with stronger relationships in larger studies at low risk of bias and with unselected populations with multiple routine blood pressure measurements. None of the systolic blood pressure measurements of <120 mmHg, <130/80 mmHg, or <140/90 mmHg were useful to rule out the development of preeclampsia (all negative likelihood ratios >0.2). Only a blood pressure measurement of ≥140/90 mmHg was a good predictor for the development of preeclampsia (positive likelihood ratio, 5.95). The findings were similar for other outcomes. CONCLUSION: Although a blood pressure of 120 to 140 over 80 to 90 mmHg at <20 weeks gestation is associated with a heightened risk for preeclampsia and adverse pregnancy outcomes and may assist in risk prediction in multivariable modelling, lowering the diagnostic threshold for chronic hypertension would not assist clinicians in identifying women at heightened risk.