Im sorry I did miss this thread - thanks for the nudge!
Yes it is based partly on aspirin, but also because of the increased knowledge of Mum and her care providers.
PE can often have warning signs which are so subtle they can be missed, in a second pregnancy though Mum is usually so knowledgeable and 'on guard' that it is picked up much earlier and managed more effectively.
You are right that if PE does recur at the 2 weeks later than before you would be 27+6 which as you say, is still to early. But that is if it recurs. Many women here will tell you about the worry they have been through dusring a second pregnancy waiting for the 'time bomb' to go off again - and it doesnt. Many will even tell you that they have set the goal they would like to reach, gone sailing past it and then dared to enjoy the remainder of the pregnancy.
You are doing all the right things, arming yourself with knowledge, it is the best defence against this horrid condition.
Close monitoring - even at home might help you feel more in charge of your pregnancy.
I hope this helps.
Every Woman is entitled to understand what happened in her pregnancy when pre eclampsia strikes. I hope to be able to support that process.