Hypertensive Disorders of Pregnancy
Definition
Hypertensive disorders of pregnancy (HDP) is an umbrella term encompassing four entities defined by the timing and features of hypertension (BP ≥140/90 mmHg) in relation to 20 weeks' gestation: (1) chronic hypertension — present before 20 weeks; (2) gestational hypertension — new-onset after 20 weeks without proteinuria/organ damage; (3) preeclampsia/eclampsia — hypertension after 20 weeks with proteinuria and/or organ damage; and (4) preeclampsia superimposed on chronic hypertension — preexisting hypertension with new or worsening proteinuria or systemic features. HDP affect 7.5% of pregnancies but 15.3% of women across their reproductive lives, and are the second leading cause of global maternal mortality (after hemorrhage).
Key Concepts
Epidemiology and Trends
- HDP affect 7.5% per pregnancy; per-woman lifetime incidence 15.3% — the latter better reflects the number of women at risk for future CVD sources/ht-pregnancy-aha-2022 (rating: high)
- CVD (including stroke and cardiomyopathy) accounts for up to 50% of all maternal deaths; pregnancy-related stroke hospitalizations increased >60% from 1994 to 2011 sources/ht-pregnancy-aha-2022 (rating: high)
- Incidence is rising due to advanced maternal age at first pregnancy and increasing prevalence of obesity and cardiometabolic risk factors
- HDP rates have nearly doubled over the past decade sources/prepregnancy-aha-2023 (rating: high)
HDP Classification (4 Types)
| Type | BP Timing | Additional Features |
|---|---|---|
| Chronic hypertension | <20 weeks (or pre-existing) | Primary (90%) or secondary |
| Gestational hypertension | ≥20 weeks | No proteinuria or organ damage |
| Preeclampsia | ≥20 weeks | + proteinuria and/or organ damage |
| Superimposed preeclampsia | <20 weeks (chronic HT) | New proteinuria or systemic features |
Immediate Maternal Complications (Selected Estimates)
- Preeclampsia: mortality aOR 2.6; MI aOR 3.0; stroke aOR 5.7; peripartum cardiomyopathy aOR 3.3 sources/ht-pregnancy-aha-2022 (rating: high)
- Preeclampsia on chronic HT: stroke aOR 7.8
- Eclampsia: stroke aOR 65.9
- HDP generally: peripartum cardiomyopathy aOR 3.2 (White), 4.0 (Black), 3.0 (Hispanic)
Immediate Fetal Complications
- SGA (<10th centile): HDP RR 1.6; preeclampsia OR 1.5
- Stillbirth: HDP RR 1.4; preeclampsia aOR 1.3
- Preterm birth <37w: preeclampsia aOR 3.1; superimposed preeclampsia aOR 4.7
- Placental abruption: preeclampsia aOR 2.3; postpartum hemorrhage: preeclampsia aOR 2.3 sources/ht-pregnancy-aha-2022 (rating: high)
Long-Term Maternal Sequelae
HDP survivors have substantially elevated future cardiovascular and metabolic risk, independent of traditional risk factors:
| Outcome | Key Risk Estimate |
|---|---|
| Hypertension | Preeclampsia OR 11.6; aHR 4.5; 10 years earlier onset |
| Heart failure | HDP HR 2.7; preeclampsia aHR 2.1 |
| Coronary heart disease | HDP aHR 1.9; preeclampsia aHR 2.1 |
| Atrial fibrillation | HDP HR 1.4; preeclampsia aHR 1.7 |
| All stroke | HDP aHR 1.8; preeclampsia aHR 1.9 |
| Vascular dementia | Gestational HT aHR 3.0; preeclampsia aHR 2.4 |
| CKD | Preeclampsia RR 2.3; gestational HT RR 1.5 |
| ESKD | Preeclampsia RR 6.6; gestational HT RR 3.6 |
| VTE | HDP OR 1.5; preeclampsia aHR 1.6 |
| Type 2 diabetes | HDP HR 1.8; preeclampsia aHR 1.8 |
Sources: sources/ht-pregnancy-aha-2022 (rating: high)
- Approximately two-thirds of HDP-associated CVD risk is mediated by established risk factors; remainder reflects HDP-specific pathogenesis (likely endothelial dysfunction and vascular remodeling)
- Women with HDP show accelerated aging: earlier onset of cardiometabolic risk factors, higher multimorbidity burden
Offspring Long-Term Outcomes
- CVD in offspring (severe preeclampsia): aHR 2.3 sources/ht-pregnancy-aha-2022 (rating: high)
- Stroke in offspring: preeclampsia HR 1.9; gestational HT HR 1.4
- Higher BMI (mean 0.36 kg/m²) and higher SBP/DBP in offspring of preeclamptic mothers
BP Measurement and Classification in Pregnancy
- Hypertension in pregnancy defined universally as ≥140/90 mmHg (two readings ≥4 hours apart)
- White coat HT prevalence: 4–30% in pregnancy; associated with higher preeclampsia risk vs normotension (RR 2.4) but lower than sustained HT
- Secondary hypertension: consider if age <35, severe/resistant, no family history, hypokalemia, elevated creatinine, or early-pregnancy albuminuria; OSA increasingly relevant given rising obesity in reproductive-age women
BP Treatment Thresholds — Controversy
- ACOG (US): treat acute HT at ≥160/110 mmHg; goal 120–160/80–105 mmHg (chronic); minimal treatment for non-severe HT
- International consensus (WHO, NICE, ISSHP, ESC): treat at ≥140/90 mmHg; target ≤135/85 mmHg
- Rationale for US conservatism: (1) short duration of pregnancy minimizes long-term benefit; (2) concern for utero-placental compromise from lower BP; (3) antihypertensive teratogenicity concerns
- CHIPS trial: tight control (achieved 133/85 mmHg) vs less tight — halved severe HT; trend toward reduced preterm birth; no adverse fetal outcomes; tighter control also reduced thrombocytopenia/elevated LFTs
- CHAP trial (published 2022, after this statement): confirmed benefit — treating mild chronic HT to <140/90 mmHg reduced composite APO without increasing SGA
- AHA statement position: supports investigating lower thresholds; endorses personalized/informed decision-making, especially in Black women and those with cardiac/renal comorbidities sources/ht-pregnancy-aha-2022 (rating: high)
Pharmacotherapy
First-line (non-severe): labetalol, methyldopa, long-acting nifedipine — no clear superiority among them
Severe acute hypertension: parenteral labetalol, parenteral hydralazine, or oral nifedipine — equivalent per Cochrane review
Avoid: atenolol (fetal growth restriction); ACEi/ARBs/direct renin inhibitors (fetal renal development); MRA/spironolactone (antiandrogenic); nitroprusside
Diuretics: generally avoided antepartum; furosemide RCT demonstrated 60% reduction in persistent postpartum HT (adjusted RR 0.40)
Postpartum HDP
- ~60% of maternal deaths occur in the first year postpartum; HDP remains a leading cause sources/ht-pregnancy-aha-2022 (rating: high)
- Prevalence: up to 8% in women without antepartum HT; up to 50% with prior preeclampsia at 6–12 weeks postpartum
- Endothelial dysfunction and altered cerebrovascular autoregulation persist postpartum — amplifying hypertension risk
- Complications: stroke, seizures, peripartum cardiomyopathy, metabolic dysregulation
- sFlt-1/PlGF ratio rate of rise is independent predictor of persistent postpartum hypertension
- NSAIDs for postpartum analgesia: conflicting data on BP effects; caution with extended use
Preconception Prevention
- Prepregnancy CVH optimization (Life's Essential 8) reduces HDP risk — see concepts/Prepregnancy-Cardiovascular-Health
- Prepregnancy obesity has a population attributable fraction for HDP of 26.5–30.3% sources/prepregnancy-aha-2023 (rating: high)
- Exercise may reduce gestational HT by ~30% and preeclampsia by ~40%; dietary interventions also reduce pregnancy-related weight gain
- Low-dose aspirin (81–150 mg/day from 12–16 weeks): reduces preeclampsia by 10–20% in high-risk women — see concepts/Preeclampsia
Racial Disparities
- Maternal mortality ratio (2016): White 13; American Indian/Alaska Native 30; Black American 41 per 100,000 live births sources/ht-pregnancy-aha-2022 (rating: high)
- HDP disproportionately affects Black, AIAN women; Black women have higher preeclampsia-related severe morbidity and mortality
- Biological factors (genetic variants) may contribute to higher preeclampsia risk in Black women, beyond social determinants alone
- Implicit racial bias in US health care worsens management of severe maternal morbidity in Black and AIAN women
- See entities/Maternal-Health-Disparities
Contradictions / Open Questions
- Treatment threshold: ACOG ≥160/110 vs international ≥140/90 mmHg — CHAP trial results now support tighter control but US guideline update lag remains; optimal treatment target for non-severe HDP not established sources/ht-pregnancy-aha-2022 (rating: high)
- HDP → CVD causality: whether HDP is on the causal pathway to CVD or a marker of shared underlying risk (preexisting endothelial dysfunction) remains unresolved; approximately one-third of HDP-associated CVD risk is not explained by traditional risk factors
- Postpartum treatment targets: no specific trial-informed BP targets for the postpartum period exist; optimal duration/intensity of postpartum antihypertensive therapy unknown
- Long-term offspring neurodevelopment: antihypertensive medication exposure in utero — long-term neurodevelopmental effects poorly studied
- De novo vs recurrent postpartum preeclampsia: distinction between postpartum aggravation of antepartum HDP and truly de novo postpartum preeclampsia is unclear; role of magnesium sulfate for seizure prevention in postpartum setting undefined
Connections
- Related to concepts/Preeclampsia — the most severe and mechanistically complex HDP subtype
- Related to concepts/Adverse-Pregnancy-Outcomes — HDP is the APO most strongly linked to long-term CVD
- Related to concepts/Prepregnancy-Cardiovascular-Health — prepregnancy CVH as modifiable HDP determinant
- Related to entities/Maternal-Health-Disparities — disproportionate HDP burden in Black and AIAN women
- Related to entities/Hypertension — BP management principles; thresholds in pregnancy context
- Related to entities/Heart-Failure — peripartum cardiomyopathy; long-term HF risk post-HDP
- Related to concepts/LQTS-Pregnancy-Management — overlapping maternal CVH risk context