I work with alternative data for investors, mostly consumer spend behavior - things like point of sale transactions and online cart contents. These have value in that you can correlate panel behaviors with a company's revenue or identify trends in the market.
But, for data like ovulation schedules or events like pregnancy, it seems that it's a lot of work (and based on the FTC ethically questionable) to see one-off events or target specific consumers a small set of products.
I must be looking at the available opportunities with some kind of blind spot, because I don't get why companies would pay for this sort of data.