Out of all the first milestones with your baby, the first "real" smile is one of the most anticipated. In an instant, your world changes – your baby smiles because she recognizes you and is genuinely happy to see you. In that instant, all the work (sleepless nights, endless diaper changes) over the past several weeks seems well rewarded because your little angel finally flashes you that pink, gummy grin.

And then for the next several days, we parents try our best to re-create that smile, for family, friends, the garbage man – basically anyone who will pay attention.

Babies give fleeting smiles as early as birth and even smile in their sleep. But, according to experts, this is a reflex action or survival instinct similar to other newborn reflexes like rooting and sucking. These first reflex smiles are innate and are believed to make newborns more appealing to keep them safer.

"I can't say that I remember the very first smile, because in the beginning so many of the little smirks were questionable," says Christine Schmid, an Arizona mother of 5-month-old Sydney. "We couldn't tell if she was smiling, if she had gas or if she was just uncomfortable. I was one of those moms that read too much and learned that in the early weeks of life a child smiles for survival reasons. If they can win the love of everyone in the room, they're likely to be fed and cared for. However, even knowing this, the first smiles were the greatest."

Expect these reflex smiles to start sometime around birth to 3 days and to last until approximately 2 months.

Sometime around your baby's 6th to 8th week (although some parents say as early as 4 weeks), the smiles become a reaction to stimuli or a "learned" smile. The grin lasts a bit longer and you can even see expression in her eyes. Babies learn to smile because they see your reaction. The joy in your face and the smiles and laughter she gets from you makes her want to repeat it, again and again.

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