If you were having a home birth then I dare say its fine, but I'm wondering whether your midwife wil be concerned that they will distract you- you may worry about what they are seeing. You never can guarantee a good birth and it could be awfully stressful for them but at the end of the day- it should be your decision. Aski the midwife and see what she thinks. She may have alternative suggestions. Perhaps they could be with you during the early stages and then wait for you and help bathe the baby etc when it comes along while you are getting yourself sorted out/ bathed etc.
mum to 3yr old and 25wk bump