Take aspirin

I’m 10 weeks pregnant with baby number 6. Last week I had booking appointment on the phone with my midwife and she has told me to start taking aspirin (150mg daily). She’s said because my first baby was small 5lbs 15oz born at 39+1, my others each got bigger and I was never told to take aspirin whilst pregnant with any of those. So why now would I have to take it based off my first baby’s weight? I couldn’t really ask her as she was quite busy and it’s not the same asking over the phone as it is face to face.

I see most commonly it’s to do with pre eclampsia. She never mentioned it to me and I’ve never had it either. I’ll be sure to ask again as I have a meeting with the Obstetrician on the 26th April