I am wondering if artificially inseminating too many times can cause pregnancy and birth issues?

I am wondering if artificially inseminating too many times can cause pregnancy and birth issues?

We A.I.'ed our English Bulldog 3 times, 2 days apart starting on day 12 of her cycle. The A.I. was successful, and I was very diligent on her diet, sodium consumption, folic acid and I gave her daily cranberry pills for water retention to help avoid water puppies that are common in the breed. She has no health issues and nothing was abnormal throughout the pregnancy. She started leaking a black with greenish color fluid, close to a week early of her due date (63 days from 1st A.I.). I knew that something was not right and got her into the vet immediately. She said that she could hear only 1 heart beat and could see 4 skeletons that looked underdeveloped. In discussing all the options, we chose to wait for her to naturally expel the puppies and keep a close eye on her. Within 24 hours she started to expel them, which they looked of all different stages of development. The first was so small and was not even recognizable as a puppy. She then continued to expel others at different stages. I took her back to the vet the next morning to make sure that they were all out as the smaller fetuses she was obviously not able to have seen on the x-rays done earlier and I was unsure of how many we were dealing with. When we went back in there, was no heartbeat; so we opted to have her given Oxytocin to expel the rest while we were at the vet clinic. I am wondering if doing the A.I. spaced out like we did could be the cause? Would it be better to only A.I. twice, for a closer development stage in the puppies. I have been able to find nothing stating the negative of this, but have found some breeders state that they do 3 matings/A.I.

Renee