I read a statistic on a USAToday Twitter graphic that 37 percent of babies have a social media account before they turn 1. The source is a Gerber.com "Millennial Moms" survey of 1,001 moms ages 18-34. It's only the third tweet down currently on their wall, so you can look if you want.
Also, 83 percent of moms post a baby photo from the delivery room, and 14 percent post those photos within an hour of delivery.
I don't know that I believe the first statistic about social media accounts. I'd be curious to see what the survey looked like and how that question was asked. I have a lot of mom friends in that age bracket with young kids, and none of them have made social media accounts for their children. I know it happens, so maybe I just have normal friends?
As for the 83 percent, I definitely believe that! The 14 percent seems about right.