Has there been a baby boom?
Actually, given the huge dropout rate, I don't think the baby boom reliably produces a larger number of active JWs. In the late 1970s and early 80s, local witness women were having lots of babies. I think it was a trend among witnesses in New Zealand. The noise in the congregations was unbearable: Either children crying and screaming or parents taking them outside and hitting them. Peaceful it was not. Most of these babies grew up and left the religion.
I think it's an easy bet that third world immigrants are a more reliable source of "increase" than those born into the religion.