The device at the center of Rowan's study - called WHOOP - is worn on the wrist. Sixty times each second, it collects data about the wearer's resting heart rate, heart rate variability, respiratory rate and sleep. WHOOP's ability to detect heart rate variability sets it apart from other devices, such as FitBit. To the best of the researchers' knowledge, this study is the first to use a wearable device to monitor heart rate data prior to, through and after pregnancy.
“Say you're sitting there with a heart rate of 60 beats a minute," Rowan said. "Your heart is not beating exactly once every second. It may be 1.5 seconds, then 0.7 seconds, then 0.8 seconds." Generally speaking, the more someone's heart rate varies, the better shape she's in.
The research team provided WHOOP devices to women who were trying to conceive, including patients from the WVU OB/GYN clinic and the local community. "By enrolling women who exercise, we made the variable pregnancy as opposed to enrolling pregnant women and then adding exercise," Rowan said.
The researchers have analyzed the data associated with 12 of the participants who have since delivered their babies. The researchers continue to scrutinize the data. But so far, the preliminary results suggest that overall, women in the study were in better shape after giving birth than before they became pregnant.
On average, the participants' heart rate variability declined each trimester. It shot up again, however, once they delivered their babies. And it stayed elevated throughout - and even after - the six-week postpartum period.
"Studies using WHOOP in non-pregnant users have shown heart rate variability to be a marker of fitness," Rowan said. "Therefore, this could indicate that fitness gains occur during pregnancy. Anecdotally, this has been suggested in the past. As this data is further analyzed, we may see that physiologic markers show this to be true."
Although the researchers initially planned this project as a pilot study, Rowan thinks the data it generated will lead to additional research into the topic. He notes that future studies could focus on women who are sedentary before they conceive but who take up exercise during pregnancy. Researchers could also explore whether women's heart rate variability or resting heart rates change a few days - or even a week - before they go into labor.
"I think it would be absolutely astounding if we were able to predict labor," he said. For a patient with a history of pre-term labor, such a prediction could help her doctor intervene to make a full-term birth more likely.
MEDICA-tradefair.com; Source: West Virginia University
