Pregnant Mom’s Obesity Linked to Increased Colorectal Cancer Risk in Her Adult Offspring

New study may help to explain rising rates of colorectal cancers in younger adults

Oakland, CA–Adult children whose mothers had a body mass index in the obese range during pregnancy may face an increased risk of colorectal cancer, according to research on more than 18,000 mother and child pairs published online in the journal Gut, a specialist journal published by the British Medical Journal with the British Society of Gastroenterology.

The findings from researchers at the Child Health and Development Studies (CHDS), a program of the Public Health Institute, and the School of Public Health at The University of Texas Health Science Center at Houston suggest that fetal conditions may be key risk factors and help to explain rising rates of the disease among younger adults.

The results showed that total weight gain of 23-29 pounds during pregnancy was associated with a doubling in risk for colorectal cancer among adult children, compared with children of mothers who gained minimal weight during pregnancy. Timing of weight gain also appeared to play a role:  a high rate of weight gain early in pregnancy was associated with a quadrupling in risk among adult children, but only among the children of mothers whose total weight gain had been low. The risk was also elevated among those with high birth weights of 8.8 pounds or more, compared with those within a healthy weight range at birth.

Fetal programming, or the concept that events in the womb have life-long effects on the health of children is thought to be a factor in several health conditions across the life course, including cardiovascular disease and diabetes. The authors note that obesity or weight gain during pregnancy may alter the fetal environment in ways that affect later health outcomes. Nutrients received in the womb may permanently alter the structure and function of adipose (fat) tissue, appetite regulation and metabolism in the children while excess exposure to insulin and growth hormone may affect insulin sensitivity, they explain.

“The 60+ year follow-up of the pregnancies and offspring in the Child Health and Development Studies makes it possible to learn how exposures in the womb might impact the health of people today,” said Dr. Barbara Cohn, director of CHDS and a co-author of the study. “Life in the womb is a critical period of susceptibility when disruption has potential for long-term consequences.”

The researchers drew on more than 18,000 mother and child pairs from the CHDS to see if maternal obesity, pregnancy weight gain, and high birth weight might be associated with a heightened risk of colorectal cancer in adulthood. At enrollment in the CHDS (1959-66), mothers provided background information, while details of prenatal visits, diagnosed conditions, and prescribed medications were gleaned from their medical records, from 6 months before pregnancy through to delivery. The offspring were then monitored for 60 years from birth until 2019 through linkage with the California Cancer Registry.

In many high-income countries, new cases and deaths from colorectal cancer have fallen or plateaued in older adults, but have nearly doubled in younger adults; rates have risen rapidly across all age groups in low- and middle-income countries. Consequently, 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.

“Our results provide compelling evidence that in utero events are important risk factors of [colorectal cancer] and may contribute to increasing rates in younger adults,” the authors write, adding: “There may also be other as yet unknown exposures during gestation and early life that give rise to this disease and warrant further study.”

“Given population trends in maternal obesity, which has multiplied in prevalence by nearly six since the 1960s, we may see a growing burden of early-onset [colorectal cancer] for decades to come,” they conclude. 

See more information on the study “Maternal obesity, pregnancy weight gain, and birth weight and risk of colorectal cancer” here.