Excessive weight gain during pregnancy linked to higher risk of severe maternal complications
· Medical Xpressedited by Sadie Harley, reviewed by Robert Egan
Sadie Harley
Scientific Editor
Meet our editorial team
Behind our editorial process
Robert Egan
Senior Editor
Meet our editorial team
Behind our editorial process Editors' notes
This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:
fact-checked
peer-reviewed publication
trusted source
proofread
The GIST Add to Preferred Sources
A new study of more than 1 million births led by McMaster University researchers has found that gaining too much weight during pregnancy, regardless of a person's starting weight, is linked to a higher risk of life-threatening maternal complications.
Current pregnancy weight-gain recommendations were developed primarily to improve outcomes for babies, such as healthy birth weight and reducing the risk of preterm birth. The study, published in JAMA Network Open, suggests the recommendations should also be evaluated through the lens of maternal health, including the risk of life-threatening complications such as bleeding, preeclampsia and ICU admission during childbirth.
Examining weight gain and severe complications
"We've long known that a person's weight before pregnancy is a risk factor. We wanted to know whether the amount of weight gained during pregnancy also influences the risk of complications," says lead author Sahar Khademioore, a Health Research Methodology Ph.D. candidate at McMaster.
"Because weight gain is something that can potentially be addressed, understanding how it relates to severe complications gives us an opportunity to better support maternal health."
Of the more than 1 million Ontario pregnancies studied using the BORN Ontario birth registry:
- 53% gained more weight than recommended.
- 19% gained less than recommended.
- More than 15,000 severe maternal morbidity cases were identified.
- Excessive weight gain increased risk across every body mass index (BMI) category.
Pre-existing conditions compound the risks
People with pre-existing conditions such as diabetes, asthma and high blood pressure faced roughly double the risk of severe maternal complications, with risks increasing further when weight gain fell outside the recommended range. Researchers also found that gaining less than the recommended amount of weight was associated with higher risks of severe maternal outcomes in some BMI groups.
"More than half of pregnancies in our study involved weight gain above current recommendations, underscoring how challenging healthy weight gain during pregnancy can be. Our findings provide important evidence for clinicians and policymakers, but supporting healthy weight gain will require more than individual counseling. We also need broader, population-level strategies that create supportive environments for healthy pregnancies," says senior author Laura Anderson, associate professor with McMaster's Department of Health Research Methods, Evidence, and Impact.
The study is part of the SERENE Project, a research effort in partnership with a lived experience advisory network that is committed to exploring why and when severe maternal morbidity happens, which people are most affected, what the long-term physical, social and mental health implications are, and how severe maternal morbidity and its negative effects can be reduced.
Publication details
JAMA Network Open (2026). DOI: 10.1001/jamanetworkopen.2026.40027
Journal information: JAMA Network Open
Key medical concepts
Clinical categories
Obstetrics & gynecologyPregnancyWeight management Provided by McMaster University Who's behind this story?
Sadie Harley
BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries. Full profile →
Robert Egan
Bachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →
Citation: Excessive weight gain during pregnancy linked to higher risk of severe maternal complications (2026, October 22) retrieved 22 October 2026 from https://medicalxpress.com/news/2026-10-excessive-weight-gain-pregnancy-linked.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.