When a child comes, there are all kinds of new expenses: diapers, formula, clothes, pediatricians, strollers, cribs, baby monitors, toys. . . .
Personally though, I'm surprised the canonical example isn't buying a new home. I bought my first home two months ago, and it seems like every day in the mail I get two offers for life insurance, another for lawn care, and another for furniture/blinds. But I'm not seeing a deluge of online ads for those things. Maybe it's an opportunity?