Confused!

Amanda 🏴󠁧󠁢󠁥󠁮󠁧󠁿 baby #4 due Summer 2020

Can anyone tell me what this bloodwork is that everyone keeps talking about?! I’m from the U.K. and had three babies, never once had bloodwork except for when I see my midwife and she is testing for the usual, blood group etc etc