Authors' objectives: For women with chronic or gestational hypertension who remain well, early term birth (at 37–38 weeks’ gestation) may reduce maternal complications, caesareans and stillbirths, but it may increase neonatal morbidity compared with expectant care. Expectant care may increase costs. There are no high-quality data to guide care, which currently involves maternal–fetal surveillance and intervention for maternal or fetal compromise, which may be rapid or unexpected. To investigate optimal timing of birth for women with chronic or gestational hypertension who reach term and remain well.

Authors' results and conclusions: From 2019 to 2022, 403 participants were randomised (37% of target 1080) to intervention (n = 201) or control (n = 202). The funder stopped the trial during the coronavirus disease discovered in 2019 pandemic for delayed recruitment. In the intervention (vs. control) group, birth was a median of 0.9 weeks earlier (38.4, interquartile range 38.3–38.6 vs. 39.3, interquartile range 38.7–39.9 weeks). There was no evidence of a difference in ‘poor maternal outcome’ (13% vs. 12%, respectively; adjusted risk ratio 1.16, 95% confidence interval 0.72 to 1.87). For ‘neonatal care unit admission ≥ 4 hours’, the intervention was considered to be non-inferior to control, as the adjusted risk difference, 95% confidence interval upper bound did not cross the 8% pre-specified non-inferiority margin (7% vs. 7%, respectively; adjusted risk difference 0.003, 95% confidence interval −0.05 to +0.06), although event rates were lower than estimated. There was no evidence of a difference in caesarean (29% vs. 36%, respectively; adjusted risk ratio 0.81, 95% confidence interval 0.61 to 1.08). Despite being unable to recruit to target in this study, we observed that most women with chronic or gestational hypertension required labour induction and planned birth at 380–3 weeks (vs. usual care), which resulted in birth an average of 6 days earlier and there were no differences in poor maternal outcome or neonatal morbidity. Our findings provide reassurance about planned birth at 380–3 weeks as a clinical option for these women.

Authors' methods: Pragmatic, unmasked, multicentre randomised trial with a health economic analysis. Fifty United Kingdom hospitals. Inclusion: maternal age ≥ 16 years, chronic or gestational hypertension, singleton pregnancy, live fetus, 36+0–37+6 weeks’ gestation and able to give documented informed consent. Exclusion: contraindication to either trial arm (e.g. pre-eclampsia), blood pressure ≥ 160/110 mmHg until controlled, major fetal anomaly anticipated to require neonatal care unit admission or participation in another timed birth trial. Planned early term birth at 38+0–3 weeks’ (intervention) or ‘usual care at term’ (control, revised from ‘expectant care until at least 40+0 weeks’, August 2022). Maternal coprimary: composite of ‘poor maternal outcome’ (severe hypertension, maternal death or maternal morbidity and superiority hypothesis). Neonatal coprimary: neonatal care unit admission ≥ 4 hours (non-inferiority hypothesis). Each coprimary is measured until primary hospital discharge or 28 days post birth (whichever is earlier). Key secondary: caesarean birth. Recruitment was 37% of the anticipated sample size (as above).

Project Status: Completed

URL for project: https://www.journalslibrary.nihr.ac.uk/programmes/hta/NIHR136141

Year Published: 2026

URL for published report: https://www.journalslibrary.nihr.ac.uk/hta/AAVV3131

URL for additional information: English

English language abstract: An English language summary is available

Publication Type: Full HTA

Country: England, United Kingdom

DOI: 10.3310/AAVV3131

Organisation Name: NIHR Health Technology Assessment programme

Contact Address: NIHR Journals Library, National Institute for Health and Care Research, Evaluation, Trials and Studies Coordinating Centre, Alpha House, University of Southampton Science Park, Southampton SO16 7NS, UK

Contact Name: journals.library@nihr.ac.uk

Contact Email: journals.library@nihr.ac.uk