The period between conception (and not of mating) and that of childbirth is called pregnancy: this period varies from 58 days to a maximum of 70 days.
It is difficult to notice before a month if the dog is pregnant, but from the thirtieth day the increase in the abdomen and the modification of the character that becomes quieter and the increase or decrease in appetite can be signs of next birth of puppies.
To be sure, the vet will subject the dog to a series of tests:
At this point it would be good to improve your diet, take frequent walks and introduce mineral or vitamin preparations around mid-pregnancy, asking your vet for advice first. It will also be necessary to deworm the dog using a product that acts gently.
However, you don't have to worry while waiting because childbirth is a completely physiological event that happens, in most dogs, very easily.
The important thing is to think about where she will have to give birth: you need to provide comfortable accommodation for the whole family by buying a box in specialized shops or, why not, practicing a cheap "do it yourself"!
The possible problems that can occur during pregnancy are: