[wxnx]

A timely study, certainly.

It's important to note that risk factors for mortality overlap significantly with the risk factors for other serious adverse events (see e.g. disability status [1], or HELPP syndrome [2]). In a sense, mortality (although fortunately rare as noted in other comments) is therefore a useful proxy for other severe, potentially life-changing adverse pregnancy-related medical events which are much more common than just plain death. (As an analogy, something like 10-15% of heart attacks are fatal, but many more are debilitating.)

[1] doi:10.1001/jamanetworkopen.2021.38414

[2] doi:10.1111/1471-0528.16225