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Hypertension in pregnancy

TL;DR — The treatment threshold in pregnancy moved decisively in 2022. CHAP randomised 2,408 women with mild chronic hypertension (<160/100 mm Hg) before 23 weeks to active treatment targeting <140/90 mm Hg versus treatment only for severe hypertension: the composite of severe pre-eclampsia, medically indicated preterm birth before 35 weeks, placental abruption, or fetal/neonatal death occurred in 30.2% versus 37.0% (adjusted RR 0.82, 95% CI 0.74–0.92), with no excess of small-for-gestational-age birth weight below the 10th centile (11.2% vs 10.4%; aRR 1.04, 0.82–1.31) (Tita 2022, PMID 35363951). That removed the long-standing fear that lowering maternal pressure starves the fetus, which had been the reason for permissive targets. CHIPS had earlier shown that less-tight control (target diastolic 100 mm Hg) produced no difference in pregnancy loss or high-level neonatal care versus tight control (target 85 mm Hg), but 40.6% versus 27.5% developed severe hypertension (Magee 2015, PMID 25629739). Aspirin from the first trimester prevents preterm pre-eclampsia in screen-positive women (Rolnik 2017, PMID 28741785). The most under-appreciated part of the field is what happens afterwards: hypertensive pregnancy roughly doubles later maternal stroke risk (aRR 1.74, 95% CI 1.45–2.10) (Brohan 2023, PMID 36990309), and postpartum self-management lowers blood pressure nine months later by 6.5/5.8 mm Hg (Kitt 2023, PMID 37950919).

Classification

The ISSHP framework distinguishes chronic hypertension (predating pregnancy or before 20 weeks), gestational hypertension (new after 20 weeks without proteinuria or organ dysfunction), pre-eclampsia (with proteinuria or maternal organ dysfunction or uteroplacental dysfunction), and pre-eclampsia superimposed on chronic hypertension (Brown 2018, PMID 29899139; Brown 2018, PMID 29803330; Tranquilli 2014, PMID 26104417). White-coat and masked phenotypes exist in pregnancy too and matter: white-coat hypertension in pregnancy is associated with subsequent pre-eclampsia (Hadizadeh 2024, PMID 37792010), and masked pregnancy-associated hypertension predicts adverse outcomes (Mussarat 2023, PMID 37098390). Out-of-office measurement therefore has a role here as elsewhere (Metoki 2022, PMID 35726086; Walker 1998, PMID 9793940), with the added complication of terminal-digit preference and threshold avoidance around the 140 and 90 mm Hg boundaries in pregnancy records (von Dadelszen 2026, PMID 42234864).

Treating chronic hypertension in pregnancy

Trial n Comparison Primary result Growth safety
CHAP (PMID 35363951) 2,408 Antihypertensives targeting <140/90 vs treatment only for BP ≥160/105 Composite 30.2% vs 37.0%; aRR 0.82 (95% CI 0.74–0.92) SGA <10th centile 11.2% vs 10.4%; aRR 1.04 (0.82–1.31)
CHIPS (PMID 25629739) 987 Less-tight (diastolic 100) vs tight (85) Pregnancy loss/high-level neonatal care 31.4% vs 30.7%; aOR 1.02 (0.77–1.35) —

CHAP's secondary outcomes moved in the same direction: any pre-eclampsia 24.4% vs 31.1% (RR 0.79, 95% CI 0.69–0.89) and preterm birth 27.5% vs 31.4% (0.87, 0.77–0.99), with serious maternal (2.1% vs 2.8%) and severe neonatal complications (2.0% vs 2.6%) numerically lower (Tita 2022, PMID 35363951). CHIPS's key finding — a 13-percentage-point excess of severe hypertension under less-tight control with no offsetting fetal benefit — pointed the same way seven years earlier without changing practice (Magee 2015, PMID 25629739; Magee 2016, PMID 27620393). CHIPS secondary analyses examined drug choice, gestational-age at initiation and cost (Magee 2016, PMID 26259808; Pels 2018, PMID 29686009; Ahmed 2016, PMID 27550914).

Post-CHAP questions being worked through include optimal delivery timing (Metz 2024, PMID 39013178), the mean-arterial-pressure–neonatal-outcome relationship (Moore 2024, PMID 38781591), whether third-trimester low maternal pressure produces small-for-gestational-age infants (Boggess 2025, PMID 40638923), and effects on postpartum control (Martin 2024, PMID 39265175). Reviews frame what has changed (Fishel Bartal 2023, PMID 37263400; Sanusi 2024, PMID 38465909).

Drug choice

Network meta-analysis of 23 randomised trials and 3,989 women found that, versus placebo or no treatment, labetalol (RR 0.20, 95% CI 0.09–0.48) and methyldopa (0.44, 0.20–0.99) reduced severe hypertension; in the network, labetalol versus nifedipine was associated with less pre-eclampsia (RR 0.50, 0.28–0.87) and less preterm birth (0.68, 0.52–0.90). Overall trial quality was low to moderate, so the authors state only "a modest favor for labetalol" (Hup 2025, PMID 40216176). Within CHAP, a comparison of nifedipine and labetalol found broadly similar outcomes (Sanusi 2024, PMID 38949541).

ACE inhibitors, ARBs and direct renin inhibitors are contraindicated in pregnancy because of fetal renal toxicity — an absolute rather than relative contraindication, and one of the few places in hypertension where drug class choice is dictated by safety rather than efficacy.

Preventing pre-eclampsia

First-trimester combined screening (maternal factors, mean arterial pressure, uterine artery pulsatility index, PAPP-A, PlGF at 11–13 weeks) detected 76.7% of preterm pre-eclampsia at a 9.2% false-positive rate in the ASPRE population of 25,797 singleton pregnancies, and aspirin 150 mg daily from 11–14 to 36 weeks reduced preterm pre-eclampsia incidence by 62% in screen-positive women (Rolnik 2017, PMID 28741785). Subsequent analyses cover adherence (Rolnik 2026, PMID 41707896), biomarker trajectories (Rolnik 2024, PMID 38151219), birthweight effects (Rolnik 2025, PMID 40590060), risk factors for pre-eclampsia despite aspirin (Shen 2021, PMID 33998099) and small-for-gestational-age prediction (Tan 2018, PMID 29704277). FIGO has issued a pragmatic implementation guide (Poon 2019, PMID 31111484), and the screening-model literature has expanded (Chaemsaithong 2022, PMID 32682859; Pooh 2024, PMID 38366809).

Self-monitoring and remote management

  • In pregnancy. BUMP 2 randomised pregnant individuals with chronic or gestational hypertension to self-monitoring with telemonitoring versus usual care and found no improvement in clinic blood-pressure control (Chappell 2022, PMID 35503345). Cost analyses of the BUMP trials have been published (Campbell 2024, PMID 38258566), and remote-monitoring syntheses are mixed (Rajkumar 2025, PMID 39611763; Aquino 2020, PMID 32301744; Hu 2025, PMID 40929717).
  • Postpartum. POP-HT randomised 220 women requiring antihypertensives at postnatal discharge after pre-eclampsia or gestational hypertension to self-monitoring plus physician-optimised titration versus usual care. At about 249 days postpartum, 24-hour mean diastolic pressure was 71.2 vs 76.6 mm Hg (difference −5.80 mm Hg, 95% CI −7.40 to −4.20) and systolic 114.0 vs 120.3 (−6.51, −8.80 to −4.22) (Kitt 2023, PMID 37950919). The imaging substudy showed less adverse cardiac remodelling (Kitt 2024, PMID 37950907) and a later analysis showed vascular remodelling effects (Kitt 2025, PMID 40905148). A qualitative study of the predecessor SNAP-HT intervention describes implementation (Cairns 2020, PMID 32517785). Postpartum management generally has now been synthesised (Tol 2026, PMID 41421750).

The contrast between BUMP 2 (null, during pregnancy) and POP-HT (large effect, postpartum) is instructive: the postpartum intervention included physician-guided titration, which is the co-intervention that made self-monitoring work in the general hypertension literature too (Tucker 2017, PMID 28926573).

Long-term maternal consequences

Outcome after hypertensive disorder of pregnancy Estimate Source
Any stroke aRR 1.74 (95% CI 1.45–2.10) (Brohan 2023, PMID 36990309)
Any stroke after pre-eclampsia 1.75 (1.56–1.97) (Brohan 2023, PMID 36990309)
Ischaemic stroke after pre-eclampsia 1.74 (1.46–2.06) (Brohan 2023, PMID 36990309)
Haemorrhagic stroke after pre-eclampsia 2.77 (2.04–3.75) (Brohan 2023, PMID 36990309)
Any stroke after gestational hypertension 1.23 (1.20–1.26) (Brohan 2023, PMID 36990309)
Ischaemic stroke after chronic hypertension in pregnancy 1.49 (1.01–2.19) (Brohan 2023, PMID 36990309)
Dementia Elevated in systematic review and meta-analysis (Schliep 2023, PMID 36345823)
Cardiovascular events, early- vs late-onset pre-eclampsia Higher after early-onset disease (Dall'Asta 2021, PMID 32484256)

These figures come from 24 studies and 10,632,808 participants (Brohan 2023, PMID 36990309). They reframe hypertensive pregnancy as a sex-specific cardiovascular risk marker identified decades before conventional risk scoring would flag the woman — and, given POP-HT, as a point of intervention rather than only of prediction. Long-term renal risk has also been examined (Barrett 2019, PMID 31061049), as have offspring effects (Wang 2022, PMID 34784738; Kazmi 2019, PMID 31230546). Hypertensive disorders of pregnancy are especially burdensome in sub-Saharan Africa (Gemechu 2020, PMID 33334273). The Lancet women and cardiovascular disease Commission places this in the broader picture (Vogel 2021, PMID 34010613).

Open questions

  • CHAP established that treating to <140/90 mm Hg is beneficial and did not increase small-for-gestational-age birth (Tita 2022, PMID 35363951). CHIPS had already randomised diastolic targets of 85 versus 100 mm Hg (Magee 2015, PMID 25629739), so the former claim that no lower target had been randomised was wrong. As of the 2026-09-01 PubMed and ClinicalTrials.gov searches, the narrower gap is whether a systolic target below 140 mm Hg improves maternal outcomes without fetal harm; GOALPOST compares <140/90 with <160/110 rather than testing a lower systolic target (NCT07746271).
  • Labetalol is modestly favoured over nifedipine on one network analysis of non-severe pregnancy hypertension (Hup 2025, PMID 40216176), but the former claim that direct trials did not exist was false. In 894 women with severe hypertension, oral nifedipine, labetalol and methyldopa were randomised head to head; the prespecified primary outcome occurred in 84%, 77% and 76%, respectively (nifedipine versus labetalol p=0.05) (Easterling 2019, PMID 31378394). A 323-person postpartum trial found six-week hypertension readmission of 1.2% with nifedipine versus 8.1% with labetalol (adjusted OR 0.12, 95% CI 0.02–0.56) (Lovgren 2025, PMID 42597172). The residual gap is a large chronic-pregnancy-hypertension trial with medication allocation randomised and maternal and neonatal clinical outcomes powered as primary endpoints.
  • Why did self-monitoring fail during pregnancy (BUMP 2) but succeed postpartum (POP-HT)? Is the difference the co-intervention, the population, or the outcome measure? (Chappell 2022, PMID 35503345; Kitt 2023, PMID 37950919)
  • Does postpartum blood-pressure optimisation reduce the doubled long-term stroke risk, or only intermediate measures? POP-HT was powered for pressure and remodelling, not events (Kitt 2023, PMID 37950919; Brohan 2023, PMID 36990309).
  • Should hypertensive pregnancy be a formal input to long-term cardiovascular risk equations, and would that change management? (Brohan 2023, PMID 36990309; Vogel 2021, PMID 34010613)

References

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