American Heart Association blood pressure classification and subsequent risk of preeclampsia.

BACKGROUND

In 2017, the American Heart Association (AHA) and American College of Cardiology updated their hypertension guidelines for the nonpregnant population, lowering the diagnostic thresholds to systolic blood pressure ≥130 mmHg or diastolic blood pressure ≥80 mmHg. This reclassification has raised important questions regarding whether blood pressure (BP) values previously considered within the normal range in pregnancy may, in fact, confer an increased risk for hypertensive disorders of pregnancy (HDPs).

OBJECTIVE

To evaluate the association between first-trimester BP classified by AHA thresholds and the subsequent development of HDPs.

STUDY

DESIGN

This was a secondary analysis of a prospective, multicenter cohort study enrolling singleton pregnancies at ≤13 6/7 weeks' gestation. Participants with preexisting hypertension were excluded. First-trimester BP was categorized using AHA guidelines: normal (<120/80 mmHg), elevated (120-129/<80 mmHg), Stage 1 hypertension (130-139/80-89 mmHg), and Stage 2 hypertension (≥140/90 mmHg). The primary outcome was preeclampsia; secondary outcomes included gestational hypertension and HDPs. Associations were evaluated using multivariable Cox regression adjusted for maternal age, body mass index, parity, race, smoking status, and preeclampsia risk factors. Predictive performance was assessed using concordance indices.

RESULTS

Among 576 participants, 13.0% developed HDP, including 7.6% with preeclampsia. Incidence of preeclampsia increased stepwise with AHA BP category: 4.8% (normal), 11.2% (elevated), 14.6% (Stage 1), and 16.7% (Stage 2) (p < 0.001). Compared to normal BP, adjusted hazard ratios for preeclampsia were 2.24 (95% confidence interval [CI], 1.03-4.86) for elevated BP, 2.80 (95% CI, 1.38-5.67) for Stage 1, and 2.48 (95% CI, 0.32-19.01) for Stage 2. AHA-based models outperformed American College of Obstetricians and Gynecologists (ACOG) thresholds (≥140/90 mmHg) in predicting HDP (C-index, 0.71 vs. 0.65; p < 0.05).

CONCLUSION

First-trimester BP classification using AHA guidelines offers a more nuanced approach to stratifying HDP risk in pregnancy, enabling earlier identification of at-risk individuals beyond the current ACOG definition of chronic hypertension in pregnancy, and supporting more personalized counseling and preventive strategies.