Ok I understand that we shouldn't open the door or in my case i have a very small round opening at the top of my hatcher , but my ? is why . Is it that we dont want to lose the humidity ? , or the small temp change ? , What makes the chick so vulnerable at that time? i pulled 3 chicks out yesterday and put them in brooder , then 2 hours later another one piped and hatched in 4 hrs . I dont lose much humidity it fell from 75% - 68% and the temp fell from 99.9 to 98.4 for only like 4 sec. So just wondering why do we (LOCKDOWN). It did not seem to bother the last chick that hatched for me .