Many women’s rights activists would laud the transition women have made since the 1960s — from stay-at-home moms, who cook and clean for the entire family — to working, independent women, who are still mothers. But a somewhat detrimental result of this shift, according to a new study, is that today’s mothers spend fewer hours engaging in physical activity, and it could be affecting not only their health but their children’s health, too.

The research found that mothers in 2010, who had children between the ages of 5 and 18, spent up to 11 fewer hours being active than mothers in 1965. Moms with kids younger than 5 spent up to 14 fewer hours. This included time spent on simple activities, such as housework, laundry, cooking, washing dishes, and taking care of the kids — and above all, exercise. But further exacerbating this trend is that these mothers were also found to spend about seven more hours watching TV or driving, both of which involve sitting in one place. The trend doesn’t only affect the moms either; leading a more sedentary life can be passed down to their children, the researchers said, and it could correlate to rising obesity rates over the past 45 years.

“A mother’s physical activity and sedentary behaviors affect the environments to which her progeny are exposed, such as the intrauterine milieu and family social setting,” lead researcher Edward Archer, a public health professor at the University of South Carolina, told the LA Times. “With each passing generation, mothers have become increasingly physically inactive, sedentary, and obese, thereby potentially predisposing children to an increased risk of inactivity, adiposity, and chronic non-communicable diseases.”

More than a third of U.S. adults are considered obese, according to the Centers for Disease Control and Prevention (CDC). At the same time, about 17 percent of children, ages 2 to 19, are obese, with the prevalence of obese kids rising three-fold since 1980 alone. Being overweight or obese puts both adults and children at risk for developing chronic diseases, such as heart disease, type 2 diabetes, and certain types of cancers.  

A July study found that kids’ TV viewing habits were undoubtedly connected to those of their parents. And while getting rid of any screen time may sound impractical, another study found that children who engaged in different kinds of screen time also gained weight, and that any increases in screen time over the course of four years were also associated with increases in weight gain.  

For the current study, researchers looked at data from the American Heritage Time Use Study, which — as the name suggests — looked at the way Americans spent their time, whether paid or unpaid. Looking at how mothers with children, ages 5 to 18, spent their unpaid time, the researchers found that mothers in 1965 spent an average of 32 hours per week being active, compared to mothers in 2010, who spent only 21 hours being active. Meanwhile, mothers who had children younger than 5 went from being active 44 hours per week in 1965 to 30 hours per week in 2010.

“The confluence of our results and other research suggests that inactivity has increased significantly over the past 45 years and may be the greatest public health crisis facing the world today,” the researchers wrote in the study. “Until the intergenerational cycle of unhealthy lifestyles is interrupted, inactivity will continue to be one of the leading causes of morbidity and mortality in the world.”

Source: Archer E, Lavie C, McDonald S, et al. Maternal Inactivity: 45-Year Trends in Mothers’ Use of Time. Mayo Clinic Proceedings. 2013.