Many call the first 3 mo the "Fourth Trimester" for that very reason. The baby is still basically a fetus in many regards. It's around that 3 mo point that th

Many call the first 3 mo the "Fourth Trimester" for that very reason. The baby is still basically a fetus in many regards. It's around that 3 mo point that they start to really respond to external stimuli in more than basic ways and start to be able to explore their environment.