ETA: Too late to edit, but the point I'm trying to make is that Amazon is able to gather data on potential customers, and it's possible, even likely, that when you get pregnant, you start to think "paying for housecleaning" is worth it, and the combination of knowing if this is true, and being able to predict (or know) when someone is pregnant through their data mining and algorithms gives them a position to advertise directly to newly expectant mothers with these housecleaning services. This is, obviously, a big advantage over their competitors.