Since the 1960s, women have been spending more and more time in formal work environments, which means less time at home, doing housework.
Thanks to technology, those who do stay home and choose to do household chores have a much easier time than women did in the '60s. Combine this with the sedentary nature of many modern jobs, the free time that technology affords us and the prevalence of televisions, computers and tablets, and women's health is negatively affected -- and is affecting the health of their children -- according to a recently released report.
"The premise of the study is that humans have engineered activity out of every domain of daily life ... from the workplace to the home ... but we are not suggesting that women should be doing more housework," said Dr. Edward Archer, a research fellow with the Arnold School of Public Health at the University of South Carolina in Columbia and lead author of the study.
"Our 'world' no longer necessitates moderate or intense physical activity. Therefore, women (and men) need to allocate more time to deliberate exercise to overcome the decrement in daily activity," he said.
The study draws from a 2011 study, based on U.S. Bureau of Labor Statistics data, that concluded that fewer jobs in the workforce requiring constant movement and heavy lifting than they did years ago, along with more time at work spent sitting behind a computer or on a phone, resulted in increased body weight in men and women and led to higher rates of obesity. However, that study focused on men and women in formal workplaces and didn't account for people who work from home, keeping a household, according to Archer, and the majority of these people are women.
The new study sought to complement the 2011 data by examining the lifestyle changes and physical activity of women at work -- and working at home -- over the past 45 years.
Archer and his colleagues gathered data from an extraordinary archive of "time-use diaries" written by thousands of women beginning in 1965 as part of the American Heritage Time Use Study, which documented the hours women spent in various activities throughout their day.
The study examined how many calories the women were probably expending in each of those tasks, and how the physical activity and energy expended each day changed over the years.
The results weren't surprising. According to the study, women spent an average of 25.7 hours a week cleaning, cooking and doing laundry in 1965. In 2010, that number was down to 13.3 hours per week.
In addition to the amount of time doing active things like housework, the study found that women also reported spending more time than ever in front of screens, whether televisions, computers or tablets.
Women in 1965 obviously didn't have computers, but on average, they spent around eight hours a week sitting and watching television, while women in 2010, who have more screens to look at, reported 16.5 hours per week.
"It's not that doing the dishes expends much more energy than putting dishes in the dishwasher," Archer said. "It's about what you do with the free time technology gives you. Do you sit and watch TV?"
But the study wasn't designed to simply look at how less-active lifestyles may be raising obesity rates among women; it also looked at something unique to their bodies: pregnancy.
"Most importantly, as women became more sedentary (not out of laziness but because of the evolution of technology), their energy metabolism became less well regulated. When a woman is pregnant, the transient hyperglycemic/hypertriglyceridemic state from inactivity and long periods of sedentary behavior induces metabolic dysfunction in their offspring, predisposing them to obesity, diabetes, cardiovascular disease and cancer," according to the study.
In other words, inactivity in one generation causes obesity, diabetes and cardiovascular disease in the next.
"The hand that rocks the cradle rules the health of the next generation. ... Children are being born with a greater number of fat cells. This is due to maternal prenatal inactivity and the fat-producing nature of sedentary behavior," Archer said.
"If we truly wish to impact obesity, we need to explain that inactivity and sedentary behavior are two of the four horsemen of the apocalypse during pregnancy (alcohol and smoking being the other two); and the effect of these behaviors last a lifetime."