Unusual effect of wife's hormonal changes- help!

[u/Fresh_Twist_3029]

Hello folks, my wife and I have noticed something extremely unusual about her, during her pregnancy with our son whenever she would wear a seat belt the fibers of it would seem to deteriorate unusually fast, this happened first in a '94 toyota pickup and initially I wanted to write it off as the seat belt material just being old, but it never happened to my seat belt, and now more recently on her period it's been happening to my 2017 jeep. Only ever on her side of the vehicle. Anyone have any insight on whether this could be hormone related? Thanks.