Around 1 month, your bundle of joy will start to smile spontaneously. Till then her smile would come as part of reflex or some internal comfort. Now she smiles as a reaction to something done. Maybe thrilled by some funny noise, seeing you clapping and singing a rhyme, playing peek-a-boo. When you baby talk with her, try making it dramatic. Vary the pitch. She loves to hear your voice as it reminds her of something comforting. When she looks attentively at you, use it as an opportunity to smile and start a conversation. She will smile back and baby talk(babble). If she smiles, immediately smile back.
What you need to know
Singing songs, rhymes, imitating animal noises, dramatic baby talking, tickling or just having seen you, are all ways by which your cutie pie is going to respond back with a big smile. If it’s an open mouth smile, she is showing more joy.