The vet should be able to determine a general idea of how many pups by around 28 days (out of 62-63). You should then talk with him/her about a possible caesarian section and spaying at the same time. I suspect this is a small breed -- toy or small terrier? If she is having difficulties with pregnancy/birthing, you really should stop breeding her and have her spayed. It would be much better for her health. If she is only having one pup at a time and has difficulty with that, you may be endangering her with more breedings. Pregnancy is hard on a bitch and then losing a pup is even harder as she then has nothing to nurse the milk out and restore her hormonal balance. Please take her to the vet for a general check-up soon and then again as directed. Good luck with the whelping. Let us know what the vet says.