Excessive growth at 28 weeks

Da

I had my routine midwife appointment this morning. She measured my fundal height as per usual, instead of measuring 28 weeks I’m measuring 34! At first the midwife thought it was a mistake as it was a student doing it, however the midwife measured me herself and I was even bigger!

I’m going for a growth scan on Wednesday, was wondering if anyone had the same thing and what turned out to be the cause?