4. Lack of Smiles
If your child doesn’t smile or show joyful expressions, then this can also suggest autism.
Usually, you should start to notice your child smiling in a big way and even laughing fairly early on. Development rates vary for everyone though, so don’t be alarmed if it doesn’t happen right away.
However, if by six months your child still hasn’t begun smiling, this might be considered to be a red flag.