Takeaways
- Most pregnancies deviate from recommended GWG. Across 1.6 million pregnancies, only 32% of women achieved gestational weight gain within recommended ranges; 23% gained below and 45% gained above guidelines.
- Both inadequate and excessive GWG carry clinical risks. GWG below recommendations increased risks of preterm birth, SGA, low birth weight, and respiratory distress, while excess GWG raised risks of caesarean delivery, hypertensive disorders, LGA, macrosomia, and NICU admission.
- Global standards are needed for diverse populations. Current guidelines rely on older, U.S.-based data from predominantly white populations; study authors support new WHO-led international standards to better reflect contemporary, multi-regional, and multi-BMI populations.
A new systematic review and meta-analysis of 1.6 million women from 40 observational studies found that 68% of pregnancies involve gestational weight gain (GWG) outside recommended ranges, with both inadequate and excessive gain linked to clinically important maternal and neonatal risks. The findings, published in The BMJ, support the World Health Organization’s (WHO’s) effort to develop global GWG standards applicable across diverse populations.1,2
Investigators reported substantial variation in maternal age, prepregnancy body mass index (BMI), and GWG patterns across world regions. Overall, 23% of women gained below recommended ranges and 45% gained above recommended ranges. Only 32% achieved GWG within current guidelines, which are largely based on Institute of Medicine (IOM) recommendations developed from predominantly white, high-income populations in the 1980s.
How are inadequate and excessive GWG associated with maternal outcomes?
Across World Health Organization BMI categories, GWG below recommendations was associated with lower birth weight, higher risk of preterm birth, small for gestational age (SGA) infants, low birth weight, and respiratory distress. Conversely, GWG above recommendations was associated with higher birth weight and elevated risks of caesarean delivery, hypertensive disorders of pregnancy, large for gestational age (LGA) infants, macrosomia, and neonatal intensive care unit (NICU) admission.
Study leaders Helene Teede, MD, and Rebecca Goldstein, PhD, emphasized the global relevance of these risks, stating that the findings “reinforce the need for international standards for healthy GWG alongside lifestyle support and public health measures to improve outcomes for mothers and babies worldwide.”1
How do GWG outcomes differ across BMI categories and regions?
Of the 1.14 million women with BMI data available, 53% had a normal BMI, while 22% had obesity and 19% were overweight. The patterns of risk were consistent across BMI groups, though magnitudes varied.
When Asian BMI criteria were applied, associations remained generally consistent, with GWG above recommendations linked with higher risk of caesarean delivery and LGA infants. However, under-gain in Asian populations showed particularly elevated risks for hypertensive disorders.
Authors noted that variability across regions reflects differences in population composition, socioeconomic conditions, food environments, and local clinical practices.
Why are updated global standards needed?
The investigators emphasize that current guidelines do not reflect contemporary global populations, nutritional environments, and rising rates of overweight and obesity. According to the authors:
“Our findings inform and support the need for optimised, evidence-based WHO international GWG reference standards based on individual patient data, applicable across the full BMI range in contemporary and diverse global populations.”
The review’s breadth—spanning 5 of 6 WHO world regions—provides an evidence base for the WHO’s ongoing initiative to create unified, globally relevant GWG standards that can guide antenatal care and support interventions in diverse settings.
What perspectives were offered in the accompanying editorial?
In a linked editorial, Annick Bogaerts, PhD, and Dominika Osicka, MD, highlighted the need for more nuanced, individualized guidance. They noted that the review “challenges the black and white logic that underpins many clinical guidelines” and suggested replacing universal warnings about exceeding weight-gain thresholds with patient-centered counseling that considers determinants of weight gain and provides non-punitive support.
They also stressed the importance of broader societal action:
“Without comprehensive, life course public health strategies, the obesity epidemic will continue across generations. Governments and (inter)national agencies must act now to support women’s health before, during, and after pregnancy, ensuring that the next generation inherits the opportunity not the risk.”
References
- BMJ Group. Two thirds of women experience too much or too little weight gain in pregnancy. Eurekalert. November 19, 2025. Accessed November 20, 2025. https://www.eurekalert.org/news-releases/1106464
- Goldstein RF, Bahri Khomami M, Tay CT, et al. 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. 2025;391:e085710. doi:https://doi.org/10.1136/bmj-2025-085710
