Hi I've got a staff that's 42 days pregnant she's quite big already scan showed 4 pups they said but could their be more

Hi I've got a staff that's 42 days pregnant she's quite big already scan showed 4 pups they said but could their be more, how many can they have first litter with only one tie

Numbers in a litter can vary greatly.
At 45 days the skeletons are visible on x-ray and a puppy count can be done, then you will know exactly what to expect.