A new study from researchers at Washington University School of Medicine in St. Louis shows that a person's risk of developing one of the most common chronic liver disorders is strongly correlated to the level of obesity of their parents.
Analyzing data from a large birth cohort in the U.K., the researchers found an association between the body mass index (BMI) of the parents while the mother was pregnant and their child's risk of developing a condition known as metabolic dysfunction-associated steatotic liver disease (MASLD). For each unit increase in BMI carried by a mother or father when measured during the first trimester of pregnancy, the child's risk of developing liver disease by the time they reached their 20s increased by up to an extra 10%.
The findings, published in Gut Feb. 24, suggest that it might be possible to reduce a child's risk of developing liver disease before they are even born.
"This changes how we think about obesity and obesity-related disease," said Yin Cao, ScD , an associate professor of surgery in the Division of Public Health Sciences at WashU Medicine and senior author on the paper. "We often oversimplify this topic by talking only about a patient's current BMI as the driving factor for disease, but here we are showing the risk factors for this liver disease may actually emerge years earlier, from the parents. This indicates a need to better define obesity's intergenerational impact and to concentrate more of our prevention and education efforts to earlier in life, including preconception, pregnancy and childhood."
Previously known as non-alcoholic fatty liver disease, MASLD is the most common form of liver disease and is characterized by deposits of fatty tissue in the liver, which can lead to inflammation, scarring and eventual loss of liver function. The condition is estimated to affect almost 40% of adults in the U.S., and the rate is projected to increase to 55% by 2040.
Stefani Tica, MD , an assistant professor of pediatrics, gastroenterology, hepatology and nutrition at WashU Medicine and the first author on the study, said that because many patients do not experience symptoms, the liver disease remains underdiagnosed, especially in younger patients.
"It's not uncommon for young adults who come in to see us to have a fair amount of scarring of their liver already that had been smoldering for quite some time," said Tica, who added that MASLD is a leading underlying reason for liver transplants. "These findings suggest that there may be an opportunity to overcome some of that developmental risk."
The role of maternal and paternal obesity
The study examined data from the UK Avon Longitudinal Study of Parents and Children , which tracked a cohort of children born between 1991 and 1992 from birth until age 24. In addition to rich data on the children's health, lifestyle and development, which were tracked with regular assessments, the study's database includes information on both parents collected prior to the birth of their child. The study began during Tica's National Institutes of Health (NIH)-funded training grant and then continued under the Biobank and Big Data Core of the WashU Digestive Disease Research Core Center, which supports WashU investigators in analyzing large-scale cohorts and biobanks.
Cao, Tica and team analyzed data from 1,933 subjects and found that approximately 10% of them had liver disease by age 24, as determined by imaging, blood and metabolic markers. After controlling for genes associated with MASLD, lifestyle and diet factors, the team found an association between parental BMI before the child's birth and their odds of the liver disease. BMI is calculated as a person's weight divided by the square of their height: a BMI unit is 1 kilogram per meter squared.
Maternal obesity was associated with 2.9 times the odds of MASLD in the child; and paternal obesity was associated with 1.7 times the odds of MASLD in the child. Overweight or obesity in both parents led to a more than threefold increase in the odds of the liver disease in their offspring. Cumulative excess body mass in childhood also had a strong influence on how much parental obesity contributed to the child's risk of MASLD.
While previous studies had indicated a connection between maternal obesity and MASLD risk in children, the connection to paternal BMI had not previously been known.
Tica said that further research is needed to explore potential mechanisms of the association between parental obesity and MASLD risk in offspring, such as through obesity-driven changes to the environmental balance of the microorganisms in the gut, or to how genes express information, that may be passed on to their children.
Cao noted that in addition to the dangers liver disease poses to a patient's health, it is also a risk factor for certain types of cancer, particularly the most common form of liver cancer as well as colorectal cancer, which has been increasing in people under age 55. She said that studies like this that track patients from birth to young adulthood are rare, and that time scale is necessary to capture the progression of a disease that is years — and generations — in development. Better screening of liver health at younger ages, and treating cases before the onset of symptoms, is a start, and so might be interventions in parental health for potential parents. The issue is urgent: approximately one-third of adults of reproductive age in the U.S. are obese.
Without interventions to address obesity, "we are going to see more diseases like MASLD in younger ages, because obesity is carrying these potential impacts forward, generation to generation, and amplifying them," said Cao.
Tica SS, Luo C, Ren D, Zong X, Thompson MD, Stoll J, DeBosch B, Tarr PI, Cao Y. Parental obesity and risk of metabolic dysfunction-associated steatotic liver disease in adult offspring: A UK birth cohort study. Gut. Feb. 24, 2026. DOI: 10.1136/gutjnl-2025-336165
This work was supported by the National Institute of Diabetes and Digestive and Kidney Disorders grant number T32DK077653, the Wellcome Trust and UK Medical Research Council grant numbers 076467/Z/05/Z, MR/M006727/1 and MR/L022206/1. This content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Dr. Cao provided consultancy services to Need and Bayer for work outside the scope of the manuscript.
About WashU Medicine
WashU Medicine is a global leader in academic medicine, including biomedical research, patient care and educational programs with more than 3,000 faculty. Its National Institutes of Health (NIH) research funding portfolio is the second largest among U.S. medical schools and has grown 83% since 2016. Together with institutional investment, WashU Medicine commits well over $1 billion annually to basic and clinical research innovation and training. Its faculty practice is consistently among the top five in the country, with more than 2,000 faculty physicians practicing at 130 locations. WashU Medicine physicians exclusively staff Barnes-Jewish and St. Louis Children's hospitals — the academic hospitals of BJC HealthCare — and Siteman Cancer Center , a partnership between BJC HealthCare and WashU Medicine and the only National Cancer Institute-designated comprehensive cancer center in Missouri. WashU Medicine physicians also treat patients at BJC's community hospitals in our region. With a storied history in MD/PhD training, WashU Medicine recently dedicated $100 million to scholarships and curriculum renewal for its medical students, and is home to top-notch training programs in every medical subspecialty as well as physical therapy, occupational therapy, and audiology and communications sciences.
