How maternal weight influences children's health and breast cancer risk

Two studies presented at the European Congress on Obesity (ECO 2025) underscore the importance of addressing overweight and obesity in women and their families, not only to optimize maternal and child health, but also to reduce long-term risks such as childhood obesity and breast cancer.

An Australian study analyzed 2,121 overweight or obese pregnant women and found that the higher the maternal BMI during pregnancy, the heavier the child's weight from birth to age 10. This link held regardless of whether the mothers received dietary and physical activity counseling or only standard prenatal care. Furthermore, paternal BMI also significantly influenced child weight at age 10.

“A woman’s BMI at the start of pregnancy impacts how her child grows until they are 8-10 years old, increasing their risk of becoming overweight or obese,” explained Professor Jodie Dodd of the University of Adelaide . Dodd highlighted that, given that approximately 50% of women begin pregnancy overweight or obese, it is crucial to support families to improve their health before pregnancy and break the intergenerational cycle of obesity.

On the other hand, a British study presented by researcher Lee Malcomson, from the University of Manchester , found that women who experience significant weight gain in adulthood and have their first child after age 30, or do not have children, have almost three times the risk of developing breast cancer compared to those who have an early first pregnancy and maintain a stable weight.

The analysis, based on data from 48,417 women, confirmed that an early first pregnancy protects against postmenopausal breast cancer , while adult weight gain increases the risk. However, no evidence was found that an early pregnancy counteracts the negative impact of adult weight gain.

"Weight gain and age at first birth interact significantly in determining breast cancer risk," Malcomson noted. "It's vital that physicians understand this combination of factors to better target lifestyle and prevention advice."

These findings reinforce the need for public health policies that promote healthy weight not only during pregnancy but throughout a woman's reproductive life, in order to improve maternal and child health outcomes and reduce the risk of diseases such as childhood obesity and breast cancer.