I'm sort of new to incubating eggs - I am on my third hatch - the first hatch was not very fertile or successful - not sure which. The second hatch of eggs from the same egg supplier was much better but I didn't do anything differently - at the end, only 9 of the 12 that had developed chicks pipped out - 3 died in the shell without pipping at all and were completely formed. Is it a terrible thing to open the bator lid after day 18 or during the hatch? I'm wondering if the loss of humidity during the hatch (because I was so excited) caused the chicks to die inside their shells. Help?