Most deer are impregnated in November and have an average gestation period of 201 days. Fawns are born in late May through June. This time period is late enough that the newborn fawns will not die from the cold weather but still have time to grow before the next winter.
Fetal growth does not occur in whitetail deer for 40 days after conception. If you were to shoot a pregnant doe one month after insemination(early December), it would not be possible to tell the doe was pregnant. If you shoot a doe two months after insemination ( early January) you could find a fetus! I have shot does at both times and seen this first hand.
This video is one that will pull at the heartstrings of anyone who has had a pregnant wife. This video reminds me of watching my kids kick inside my wife’s belly.