Infants whose mothers were obese during pregnancy may have a heightened risk of developing colorectal cancer later in life, according to new research published by Murphy et al in the journal Gut. Obesity is already a well-established risk factor for colorectal cancer, and several studies suggest fetal or developmental origins of obesity may influence cancer development in adulthood.

“Maternal obesity and pregnancy weight gain may be related to colorectal cancer in offspring in two different ways,” said Caitlin C. Murphy, PhD, MPH, coauthor of the study and Associate Professor in the Department of Health Promotion and Behavioral Sciences at UTHealth School of Public Health in Houston. “First, these maternal characteristics increase [the] risk of obesity in adult offspring, and obesity is a well-known risk factor of colorectal cancer; second, they may affect the developing gastrointestinal tract in the womb, making offspring more sensitive to colorectal cancer later in life.”

Analysis Details

The team of researchers analyzed data from the Child Health and Development Studies, a prospective cohort of women receiving prenatal care between 1959 and 1966 in Oakland, California. For 60 years, researchers tracked the health of more than 18,000 of the offspring—about two-thirds of whom were White and 52% of whom were born into families whose total income fell below the national media—to determine which ones had developed colorectal cancer in adulthood through 2019.

Results

The team found that adult children whose mothers were obese during pregnancy faced more than double the risk of developing colorectal cancer compared with the adult offspring of healthy weight or underweight mothers.

Timing of maternal weight gain was also associated with risk, regardless of a mother’s obesity, according to the study. For mothers whose entire weight gain during pregnancy was lower than 20 lb, more weight gain early in pregnancy further increased the risk of colorectal cancer among adult children.

Another determinant was birth weight. Infants who weighed more than 8.8 lb at birth had a greater chance of developing colorectal cancer as adults, researchers discovered.

The group’s findings come at a critical time, according to Dr. Murphy. Given the increasing prevalence of maternal obesity and pregnancy weight gain, the global burden of colorectal cancer is expected to increase by 60%, to more than 2.2 million new diagnoses and 1.1 million deaths by 2030.

“Rates of colorectal cancer have increased rapidly in younger adults, but we know very little about what may explain this increase,” Dr. Murphy said. “These findings suggest that exposure in the womb—or in utero events—are important risk factors of colorectal cancer and may contribute to increasing rates of disease.”

Disclosure: The research is supported by funding from the National Cancer Institute. For full disclosures of the study authors, visit gut.bmj.com.