Both Low and High Weight Gain During Pregnancy Linked to Complications: A Global Analysis
An analysis covering 1.6 million pregnancies shows that both low and high weight gain can drive major complications, from preterm birth to C-sections. This raises urgent questions about how global guidelines should evolve for today’s diverse populations.
!Gaining to little or too much weight in pregnancy affects birth outcomes
Study: Gestational weight gain and risk of adverse maternal and neonatal outcomes in observational data from 1.6 million women: systematic review and meta-analysis. Image credit: Natali Kuzina/shutterstock.com
A systematic review and meta-analysis of observational data from 1.6 million women provide evidence on the association between weight gain during pregnancy (gestational weight gain) and risks of adverse outcomes in both mothers and newborns across diverse world regions and income settings. The findings are published in the British Medical Journal (BMJ).
Why gestational weight guidelines need updating
Gestational weight gain is known to be associated with acute and long-term health risks in both mothers and newborns. The Institute of Medicine (IOM) in the USA generated gestational weight gain guidelines in 1990 to optimize these outcomes, notably low birth weight.
These guidelines were developed based on a moderate-sized population of mostly White US women with a mean body mass index (BMI) of 24 and an age of 26 years.In 2009, the guidelines were updated to incorporate World Health Association (WHO) BMI categories and broader health outcomes. Since then, these guidelines have provided an significant international reference point.
The populations that formed the basis of these guidelines were characterized by lower maternal age and BMI, with limited ethnic and socioeconomic diversity. substantial variations in global population characteristics highlight the need for developing region-specific guidelines on gestational weight gain.
global population trends over the past two decades have indicated an increase in maternal age, BMI, and gestational weight gain, further highlighting the urgent need for updated guidelines based on contemporary populations across diverse world regions and income settings.
The current systematic review and meta-analysis aimed to inform the WHO’s initiative to develop global standards for gestational weight gain.
A total of 40 observational studies with 1.6 million female participants aged over 18 years were analyzed to report maternal and infant outcomes stratified by participants’ BMI and gestational weight gain.
The study also evaluated additional outcomes such as gestational diabetes and neonatal jaundice, although these were less consistently reported across included studies.
Weight gain patterns alter risks
This systematic review and meta-analysis included contemporary evidence (2009-2024) from 1.6 million women across five WHO world regions. About 53 % of these women had normal BMI before pregnancy,6 % were underweight,19 % were
Okay,here’s a breakdown of the core details from the provided text,formatted for clarity. I’ll categorize it into key findings, limitations, and implications for global guidance.
CORE INFORMATION: Gestational Weight Gain & Pregnancy outcomes – A Meta-Analysis
1. key Findings (Relationships between Gestational Weight Gain and Outcomes):
* Insufficient Gestational Weight Gain (Below Recommended Range):
* Higher risk of hypertensive disorders of pregnancy (particularly in Asian women, but see limitations below).
* Higher risk of small-for-gestational-age infants.
* Higher risk of low birth weight.
* Higher risk of respiratory distress.
* Excessive Gestational Weight Gain (Above Recommended Range):
* Higher risk of Cesarean delivery.
* Increased birth weight.
* Higher risk of hypertensive disorders of pregnancy.
* Higher risk of large-for-gestational-age infants.
* Higher risk of macrosomia (large birth weight).
* Higher risk of Neonatal Intensive Care Unit (NICU) admission.
* Lower risk of preterm birth and small-for-gestational-age infants.
* Large-for-gestational-Age/Macrosomia: Consistently linked to both insufficient and excessive weight gain.
* obesity & LGA: Women in the lowest obesity category (lowest BMI within the obese range) had a higher risk of large-for-gestational-age infants compared to other obesity categories. (This finding requires cautious interpretation – see below).
2. Limitations & Uncertainties:
* Asian Studies & BMI Classification: Significant heterogeneity (variability) in Asian studies due to differing BMI classification systems (WHO vs.regional). This makes it difficult to draw firm conclusions about population-specific risks in Asia. 60% of the world’s population lives in Asia, making this a critical gap in knowlege.
* BMI & Weight Loss in Obesity: The safety and implications of weight loss during pregnancy in women with obesity (BMI in the obese range) are uncertain.
* Obesity Class Comparisons: while subgroup analyses were done by obesity class, definitive comparative conclusions were not drawn. Patterns observed should be interpreted cautiously.
* Standardized Reporting: Lack of standardized methods for reporting BMI and gestational weight gain categories across studies introduces variability.
3. Implications for Global Guidance (WHO Initiative):
* Evidence Base: This systematic review and meta-analysis provides valuable evidence to inform the WHO’s development of globally relevant guidelines for gestational weight gain.
* Need for Diversity: Highlights the importance of including diverse populations from different world regions (especially Asia) in developing these standards.
* Future Research: Identifies key gaps in knowledge and priorities for future research, including:
* Broader range of outcomes studied.
* Standardized reporting of BMI and gestational weight gain.
* Further investigation of weight loss in obese pregnant women.
* Complements Existing Data: This review adds to existing individual patient data, providing a broader perspective.
Source:
* Goldstein RF. 2025. Gestational weight gain and risk of adverse maternal and neonatal outcomes in observational data from 1.6 million women: systematic review and meta-analysis. BMJ. https://doi.org/10.1136/bmj-2025-085710
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