For reasons scientists don't fully understand, women in their 20s, 30s and 40s tend to develop cardiovascular-disease risk factors much faster than men of similar ages do. West Virginia University epidemiologist Bethany Barone Gibbs is exploring what role adverse pregnancy outcomes -; like preeclampsia and gestational diabetes -; play in that disparity. She's also exploring whether physical activity can reduce or eliminate it.
The National Heart, Lung and Blood Institute has awarded her study $3 million.
"People always think that men have more cardiovascular disease than women," said Gibbs, who chairs the Department of Epidemiology and Biostatistics in the WVU School of Public Health. "But what happens is that women typically have lower risk factors for cardiovascular disease before their childbearing years. Then, between their 20s and 40s, they have this accelerated risk development. The incidence of hypertension and other risk factors increases in women compared to men, so they sort of catch up. We think that might be at least in part because of pregnancy exposures."
She and her colleagues will equip more than 3,000 women with a special accelerometer they'll wear on their thigh.
An accelerometer is a device that continuously measures how much time someone spends lying down, sitting, standing, stepping or cycling.
The women will wear the accelerometer 24 hours a day, for one week. They'll also have four cardiovascular-disease risk factors measured: BMI, cholesterol, blood pressure and glucose.
In addition, a subset of participants will undergo subclinical assessments for arterial stiffness and heart rate variability -; functional measures of their cardiovascular health that can detect the beginnings of cardiovascular disease long before symptoms occur.
Gibbs and her team will investigate any associations that emerge among the participants' pregnancy history, cardiovascular health, cardiovascular-disease risk factors and sedentary behavior.
Sedentary behavior includes sitting while you drive, reclining while you type on a laptop, lying down while you scroll social media and many other everyday activities.
We're not just thinking about exercise. We're thinking about sitting. We're thinking about patterns. How healthy are the people who sit a lot but also exercise a lot? Are they OK? What about people who don't exercise but don't sit very much? Are they OK? We will have the data to be able to look at all of these relationships very carefully."
Bethany Barone Gibbs, WVU epidemiologist
The researchers will choose their study participants from among the 10,000 women in a larger pregnancy study -; called NuMoM2b, or Nulliparous Pregnancy Outcomes Study Monitoring Mothers-to-Be -; a decade ago.
The women who enrolled in NuMoM2b were all pregnant for the first time. The researchers captured a wealth of data over the course of their pregnancies 10 years ago, including diagnoses of adverse pregnancy outcomes.
Gibbs' new project is a follow-up to NuMoM2b. It's part of a national cohort investigation, involving multiple institutions, called the NuMoM2b Heart Health Study.
By overlaying data from the participants' past pregnancies, present sitting and activity levels, and cardiovascular biomarkers, Gibbs and her team will be able to paint a more complete portrait of how sedentary behavior and adverse pregnancy outcomes influence women's risk of cardiovascular disease as they approach middle age.
What they discover could help health care providers recommend healthy activity patterns and estimate women's cardiovascular-disease risk more accurately. It might also help women with a history of adverse pregnancy outcomes use physical activity to lower that risk.
"We're in the business of trying to understand if therapeutic lifestyle interventions that reduce sitting, increase physical activity or both can help reduce risk in women overall, but specifically in women that have an elevated risk because of their pregnancy history," Gibbs said.
Being sedentary is a cardiovascular-disease risk factor that's distinct from not getting enough exercise. And that's true regardless of your gender or whether you've been pregnant.
In other words, if you spend 12 of your waking hours sitting at a desk, on a couch or in a car, you can't "run off" those long, sedentary blocks of time by taking a half-hour jog.
"I've done a lot of these studies where we say to people, 'Bring your work. We're going to make you sit for a whole workday, and we're going to measure what happens,'" Gibbs said. "And what we find is that, in people who sit for a long time, there's this negative cardiovascular cascade that happens, even healthy people. Blood pools in the lower legs, blood pressure increases, and your body doesn't metabolize blood sugar as well. So, we recommend that people try to just stand up for at least 15 minutes of each hour. And if you can, take a two-minute walk just once an hour. Find a way."