Murphy CC, Cirillo PM, Krigbaum NY, et al. - In a population-based cohort of more than 18,000 mother-child dyads, in utero events are important risk factors for colorectal cancer (CRC) and may contribute to rising incidence rates in younger adults.

• The Child Health and Development Studies are a prospective cohort of women who received prenatal care in Oakland, California between 1959 and 1966 (N =18,751 live births among 14,507 mothers).

• Over the course of 738,048 person-years of follow-up, 68 offspring were diagnosed with CRC, with half (48.5%) being diagnosed before the age of 50.

• Obesity in the mother (≥ 30 kg/m ²) increased the risk of CRC in the offspring.

• Total weight gain altered the association of early weight gain rate, implying that discordant growth from early to late pregnancy increases risk.

• Birth weight (≥ 4,000 g) was associated with a higher risk.