A global review of more than 1.6 million pregnancies shows that most pregnant people gain either too little or too much weight, patterns linked to significant health risks for both parent and newborn. The findings, published in The BMJ, strengthen the World Health Organization’s (WHO’s) effort to establish international standards for gestational weight gain (GWG).
Researchers analyzed 40 observational studies from diverse regions. They found that 68% of pregnancies involved GWG outside recommended ranges: 23% below and 45% above current guidelines. Only 32% of participants met existing targets, which are largely based on Institute of Medicine recommendations created in the 1980s using predominantly white, high-income populations.
Health Risks Linked To Inadequate And Excessive Weight Gain
Across all WHO body mass index (BMI) categories, gaining less than recommended was tied to lower birth weight, higher rates of preterm birth, small-for-gestational-age infants, and neonatal respiratory distress.
Excessive weight gain was associated with cesarean delivery, hypertensive disorders of pregnancy, large-for-gestational-age infants, macrosomia, and higher rates of neonatal intensive care admission.
Study leaders Helene Teede, MD, and Rebecca Goldstein, PhD, emphasized that these patterns appear consistently across global settings, underscoring the need for unified guidance and preventive support during pregnancy.
Differences By Bmi And World Region
Among the 1.14 million participants with BMI data, 53% had a normal BMI, while 22% had obesity and 19% were overweight. Although the direction of risk remained consistent across BMI groups, the magnitude varied.
When Asian BMI criteria were applied, excessive gain continued to increase the likelihood of cesarean birth and large-for-gestational-age infants. Notably, inadequate gain in Asian populations was associated with particularly high rates of hypertensive disorders. Regional differences in socioeconomic conditions, food environments, and clinical practices contributed to wide variation in outcomes.
Why Global Standards Need Updating
Investigators noted that current guidelines no longer reflect today’s populations or nutrition environments, especially amid rising global rates of overweight and obesity. Their findings support the WHO’s initiative to build updated, data-driven GWG charts suited to diverse populations and usable across the full BMI spectrum.
Expert Commentary Highlights Need For Individualized Care
An accompanying editorial called for more personalized counseling rather than rigid thresholds. We urged clinicians to consider the factors that influence weight gain and to offer supportive, non-punitive care. They also emphasized that lasting improvement requires broader public health action.
“Without comprehensive strategies across the life course,” they wrote, “the obesity epidemic will continue across generations.” They called on governments and international agencies to strengthen support for health before, during, and after pregnancy.
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