Also- thanks for taking questions and congrats on your success :)
Our growth has been remarkably steady, with minor seasonal factors. If the majority of your acquisition channels scale with the number of users (SEO, social, viral) then you should see a steady accumulation of momentum over time, even from a very small number — perhaps the low thousands.
We've had a strong word of mouth factor from the very beginning, but I attribute that mostly to the brand and the fact that this is an underserved market. Parents have traditionally been invisible to tech companies and they are delighted someone is finally building for them.