Do lower antenatal blood pressure cut-offs in pregnant women with obesity identify those at greater risk of adverse maternal and perinatal outcomes? A secondary analysis of data from the UK Pregnancies Better Eating and Activity Trial (UPBEAT)

L Slade; N Syeda; H D Mistry; J N Bone; M Wilson; M Blackman; L Poston; K M Godfrey; P von Dadelszen; L A Magee; UPBEAT Consortium

doi:10.1038/s41366-025-01803-8

Do lower antenatal blood pressure cut-offs in pregnant women with obesity identify those at greater risk of adverse maternal and perinatal outcomes? A secondary analysis of data from the UK Pregnancies Better Eating and Activity Trial (UPBEAT)

Int J Obes (Lond). 2025 Jun 16. doi: 10.1038/s41366-025-01803-8. Online ahead of print.

Authors

L Slade^{1

2}, N Syeda³, H D Mistry³, J N Bone^{4

5}, M Wilson³, M Blackman³, L Poston³, K M Godfrey⁶, P von Dadelszen^#³, L A Magee^#⁷; UPBEAT Consortium

Collaborators

UPBEAT Consortium:
Andrew Shennan, Lucilla Poston, Annette Briley, Claire Singh, Paul Seed, Jane Sandall, Thomas Sanders, Nashita Patel, Angela Flynn, Shirlene Badger, Suzanne Barr, Bridget Holmes, Louise Goff, Clare Hunt, Judy Filmer, Jeni Fetherstone, Laura Scholtz, Hayley Tarft, Anna Lucas, Tsigerada Tekletdadik, Deborah Ricketts, Carolyn Gill, Alex Seroge Ignatian, Catherine Boylen, Funso Adegoke, Elodie Lawley, James Butler, Rahat Maitland, Matias Vieira, Dharmintra Pasupathy, Nina Khazaezadeh, Eugene Oteng-Ntim, Jill Demilew, Sile O'Connor, Yvonne Evans, Susan O'Donnell, Ari de la Llera, Georgina Gutzwiller, Linda Hagg, Stephen Robson, Ruth Bell, Louise Hayes, Tarja Kinnunen, Catherine McParlin, Nicola Miller, Alison Kimber, Jill Riches, Carly Allen, Claire Boag, Fiona Campbell, Andrea Fenn, Sarah Ritson, Alison Rennie, Robin Durkin, Gayle Gills, Roger Carr, Naveed Sattar, Scott Nelson, Therese McSorley, Hilary Alba, Kirsteen Paterson, Janet Johnston, Suzanne Clements, Maxine Fernon, Savannah Bett, Laura Rooney, Sinead Miller, Paul Welsh, Lynn Cherry, Melissa Whitworth, Natalie Patterson, Sarah Lee, Rachel Grimshaw, Christine Hughes, Jay Brown, Kim Hinshaw, Gillian Campbell, Joanne Knight, Diane Farrar, Vicky Jones, Gillian Butterfield, Jennifer Syson, Jennifer Eadle, Dawn Wood, Merane Todd, Asma Khalil, Deborah Brown, Paola Fernandez, Emma Cousins, Melody Smith, Jane Wardle, Helen Croker, Laura Broomfield, Keith Godfrey, Sian Robinson, Sarah Canadine, Lynne Greenwood, Stephanie Amiel, Catherine Nelson-Piercy, Gail Goldberg, Daghni Rajasingham, Penny Jackson, Sara Kenyon, Patrick Catalano

Affiliations

¹ Robinson Research Institute, The University of Adelaide, Adelaide, SA, Australia.
² Department of Obstetrics and Gynaecology, Women's and Children's Hospital, Adelaide, SA, Australia.
³ Department of Women and Children's Health, School of Life Course and Population Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK.
⁴ British Columbia Children's Hospital Research Institute, University of British Columbia, Vancouver, BC, Canada.
⁵ Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, BC, Canada.
⁶ MRC Lifecourse Epidemiology Centre and NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK.
⁷ Department of Women and Children's Health, School of Life Course and Population Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK. Laura.A.Magee@kcl.ac.uk.

^# Contributed equally.

PMID: 40523926
DOI: 10.1038/s41366-025-01803-8

Abstract

Background: Obesity is a major risk-factor for adverse pregnancy outcomes. While the 2017 American College of Cardiology/American Heart Association (ACC/AHA) classification of normal and abnormal blood pressure (BP) outside pregnancy has been suggested for use in pregnancy, the impact on adverse outcomes has not been examined specifically in women with obesity.

Methods: The UK Pregnancies Better Eating and Activity Trial (UPBEAT) enroled women with a body mass index (BMI) ≥ 30 kg/m². In secondary analyses, maximal antenatal BP was categorised by 2017 ACC/AHA criteria: 'Normal' BP (systolic [sBP] <120 mmHg and diastolic [dBP] <80 mmHg), 'Elevated' BP (sBP 120-129 mmHg and dBP <80 mmHg), 'Stage 1 hypertension' (sBP 130-139 mmHg and/or dBP 80-89 mmHg), and 'Stage 2 hypertension' (sBP ≥140 mmHg and/or dBP ≥90 mmHg, non-severe [sBP 140-159 mmHg and/or dBP 90-109 mmHg] and severe (sBP ≥160 mmHg and/or dBP ≥110 mmHg). Main outcomes were preterm birth, postpartum haemorrhage (PPH), birthweight <10th centile (small-for-gestational age, SGA), and neonatal intensive care unit (NICU) admission. Associations with adverse outcomes were adjusted for UPBEAT intervention, maternal age, booking BMI, ethnicity, parity, smoking, alcohol, and previous pre-eclampsia or gestational diabetes. Diagnostic test properties (positive and negative likelihood ratios, -LR and +LR) were assessed as individual categories (vs. 'Normal' BP), and as threshold values.

Results: Severe 'Stage 2 hypertension' (vs. BP < 160/110 mmHg) was associated with PPH (RR 2.57 (1.35, 4.86)) and SGA (RR 2.52 (1.05, 6.07)) only in unadjusted analyses. No outcomes were associated with 'Stage 1 hypertension' or 'Elevated BP'. All +LR were <5.0 and -LR ≥ 0.20, indicating that no BP threshold was useful as a diagnostic test to detect preterm birth, PPH, SGA, or NICU admission.

Conclusions: Among pregnant women with obesity, we found no evidence that lowering the antenatal BP considered to be abnormal (from 140/90 mmHg) would assist in identifying women and babies at risk.