The women's teams of England and New Zealand will wear instrumented mouthguards that record data in training and in two upcoming matches between the two sides as part of a head impact study, World Rugby said on Friday.
The devices contain an impact monitor data acquisition system that collects and transmits data every time there is a collision between players or players and the ground.
Every impact, including those that are not directly involving the head, will be recorded by the mouthguards and be matched to time-coded video for analysis.
The initiative is part of World Rugby's six-point player welfare plan with a focus on head impact prevention, which was launched in July.
"It's great for the Black Ferns to be involved, especially because it will help improve the knowledge around female rugby players. We're also proud to be playing a role in improving the game and making it safer for everyone," New Zealand captain Les Elder said.
The devices are developed by U.S.-based Prevent Biometrics, who have already been working with World Rugby and more than 700 grassroots players in New Zealand.
World Rugby chief medical officer Eanna Falvey said: "We are delighted that the top two ranked women's international teams have joined this landmark study... we will have data from well over 1,000 participants at every level of the game recorded via the same comparable technology, which is vital for comparison and accuracy purposes."
England and New Zealand face each other at Exeter's Sandy Park on Sunday before a second meeting a week later.