NIHR Oxford Biomedical Research Centre

Enabling translational research through partnership

MENUMENU
  • About
    • About the NIHR Oxford Biomedical Research Centre
    • A Guide to What We Do
    • Activities during COVID-19
    • Strategic Partnership Board
    • Steering Committee
    • Promoting Equality, Diversity and Inclusion in Research
    • Current Vacancies
    • Contact Us
    • Stay in Touch
  • Research
        • OUR 20 RESEARCH THEMES

        • Antimicrobial Resistance and Modernising Microbiology
        • Cardiovascular
        • Clinical Informatics and Big Data
        • Diabetes and Metabolism
        • Gastroenterology and Mucosal Immunity
        • Genomic Medicine
        • Haematology and Stem Cells
        • Imaging
        • Molecular Diagnostics
        • Multi-Modal Cancer Therapies
        • Multi-Morbidity and Long-Term Conditions
        • Musculoskeletal
        • Neurological Conditions
        • Obesity, Diet and Lifestyle
        • Partnerships for Health, Wealth and Innovation
        • Respiratory
        • Stroke and Vascular Dementia
        • Surgical Innovation and Evaluation
        • Technology and Digital Health
        • Vaccines for Emerging and Endemic Diseases
        • Oxford Biomedical Research Centre activities during COVID-19
  • Patient & Public Involvement
    • Getting involved with research
    • Researcher Guidance
    • Post an opportunity for patient and public involvement
  • Training Hub
    • Training Hub Overview
    • Clinical Academic Pathway
    • Internships
    • Preparatory Research Fellowships
    • Senior Research Fellowships
    • Research Training Bursaries
    • Doctoral Awards
    • Post-Doctoral Awards
    • Other funding
    • Leadership Training
    • Useful Links
    • Training and Education Resources
    • Upcoming Training Events & Courses
  • Industry
    • Collaborate with Oxford BRC
    • What Can We Do For Your Organisation?
    • Who Do We Work With?
    • IP and Licensing
    • Contacts for Industry
  • Videos
  • News
  • Events

News

You are here: Home > Technology and Digital Health > Heart rate rise and blood pressure drops during pregnancy not as dramatic as previously thought

Heart rate rise and blood pressure drops during pregnancy not as dramatic as previously thought

11 September 2019 · Listed under Technology and Digital Health

New analysis from over 36,000 healthy women in 20 countries suggests that physiological changes during pregnancy may not be as dramatic as traditionally taught. However, blood pressures do appear to be increasing year on year.

Medical text books are based on data that is now over 40 years old. The new research by researchers at the University of Oxford, and supported by the NIHR oxford Biomedical Research Centre, includes much more recent data.

The new findings, published in BMC Medicine, show that changes to women’s blood pressure and heart rate during pregnancy are not as striking as previously thought.

Traditionally, medical text books have taught students that blood pressure drops by 10-15mmHg during the middle of pregnancy. These text books are based on old data and quite small numbers of pregnant women.

The new analysis, which is based on a much larger sample size, shows that the lower diastolic blood pressures seen mid-pregnancy are on average just 1-2 mmHg lower than the measurements taken around week 10.

This is a much smaller drop than that suggested in the text books. The analysis also shows that, on average, systolic blood pressure rises very slightly through pregnancy.

Blood pressure in pregnant women has increased slightly each year since 1967. This may be a result of pregnant women generally being older and heavier. Blood pressures are similar for those women pregnant with their first baby as for those who already have children.

The analysis also included heart rate measures from just over 8,000 women. The increase in heart rate during pregnancy is also much less than previously thought. Rather than the 20-30% increase (~15-20 beats per minute) suggested in earlier publications, newer data suggest that heart rates increase by just seven to eight beats per minute. This is closer to a 10% rise.

All pregnant women should have their blood pressure and heart rate monitored when they are admitted to hospital. This helps clinical staff make decisions about when patients need additional treatment.

Most UK hospitals check individual patients’ results against a Modified Early Obstetric Warning Scores (MEOWS) to monitor women during pregnancy. This is a version of the National Early Warning Score used across the NHS that has been adjusted to account for physiological changes during pregnancy.

However, MEOWS differ between hospitals and use warning thresholds for blood pressure and heart rate based on expert opinion rather than evidence. This new report provides reliable evidence-based ranges of blood pressure and heart rate to allow women with worsening health to be identified more quickly and accurately, throughout pregnancy.

Dr Lucy Mackillop, Consultant Obstetric Physician and one of the authors, says: “This is an important study challenging the widely held view of the expected changes to vital signs during pregnancy.

“This highlights the importance of evidence-based medicine to support and plan clinical care. Evidence-based early warning scores specific to pregnant woman are urgently needed and this study should inform their development.”

Dr Peter Watkinson, Consultant Intensive Care Physician and Co-lead for the Oxford BRC’s Technology and Digital Health theme, says: “It is really important that we understand what are normal changes during pregnancy. This new analysis allows us to identify and treat the small proportion of pregnancies where blood pressure changes are outside the normal range.”

← Smartphone test predicts how symptoms develop in Parkinson’s
Top accolade for gestational diabetes app →

News

  • Study highlights ongoing COVID-19 risk in some cancer patients despite vaccination 24 May 2022
  • BRC study outlines researchers training needs and barriers 20 May 2022
  • Three new Blood and Transplant Research Units created in Oxford 18 May 2022
See full news archive

News Categories

Month Archives

Subscribe to the Oxford BRC Newsletter

Keep informed about the work of the Oxford BRC by subscribing to our Mailchimp e-newsletter. It is produced several times a year and delivers news and information about upcoming events straight to your inbox.

Subscribe Now

Oxford BRC on Social Media

  • Facebook
  • LinkedIn
  • Twitter
  • YouTube

Feedback

We’d love to hear your feedback. Please contact us at obrcenquiries@ouh.nhs.uk

  • Sitemap
  • Data Control and Privacy
  • Accessibility
  • Our Partners
  • Disclaimer
  • Contact

Copyright © 2022 NIHR Oxford Biomedical Research Centre