Hi Soph
Basically what happened to me with ds1- did go to eclampsia there but wasn't picked up and also ther is a family history (MIL didnt tell us that until afterwards f course, and sisters had their babies after me so history was still to come if that makes sense in a bizarre way?)
Basically if the bllod flow fails it can be a danger to the placenta and cause the baby to develop IUGR as ds1 did (losta round a pound in utero, which put him at 5 lb 5 oz born, and he lost a pound or more afterwards as well). There's an onbvious risk if this isn't picked up earlya s ds1 was induced early, even then ds1 has SN which may or may not be related to the IUGR.
I don't know that exact stas and would emphasise that nobody knows the aetiology of eclampsia and rpe eclampsia for certain- I am on the committee of a pre-eclampsia suport group (pre eclampsia and toxaemia society, on the internet) and sometimes help edit their papers and nothing is certain; but there does seem to be a link there. But its a complex one- family histories, amternal age, etc alls eem to play a part too.