Car Park 8 is right next to The Maternity Ward but it's pretty small and you'll struggle to get a space in there. Your best bet would be to go right past car Park 8, take a right onto Hardgate Road and go into the multi storey, looks like that is Car Park 1 according to google.
It's just round the corner and only about a 3 or 4 minute walk to the maternity ward from there.