Earlier quoted context omitted.
Leading cause of death under one year is sudden infant death syndrome which happens mostly at nap time, situations where the adult may need rest, self care or housekeeping. You cannot fathomly watch an infant 24/7 especially if one parent is working and there's minimal support sistem (living far from relative, working grandparents etc)
"Measures not shown to be useful include positioning devices and baby monitors." https://en.wikipedia.org/wiki/SIDS
ox and hearth rate baby monitor definitely alert on sids. prevent, no, and that's why they are not medical devices, and wouldn't make sense to pay a randomized controlled trial to certify as one.
works? yeah. hearth stops beating, ox goes under parameter, parents get an alert.
here's the FDA statement about it https://www.accessdata.fda.gov/cdrh_docs/pdf22/K222597.pdf