Eclampsia and pre-eclampsia are still little understood in real terms.
Once you move from pre-eclampsia to full blown fitting (eclampsia), there is absolutely no treatment. The same is true today.
MIL went for her 31wk appointment when pg with DH and ended up being bluelighted to London and having an emcs at St Thomas'. FIL was told to expect to lose both of them. She was severely ill and probably less than an hour away from developing full blown eclampsia.