This theme of anecdote has been trotted out for more than a half century. In the 80’s the yarn was that a supermarket could tell when a woman was pregnant before her doctor from her purchase patterns alone.
To this date, no supermarket has ever produced this result - or any thematically similar.
target
Target’s able to confidently estimate that a woman is pregnant from 20 weeks from their purchase history, if they’d purchased pregnancy tests. A doctor can tell you 70+ days earlier.
They’d probably have an equivalent outcome if they just looked at cctv footage and guessed based on weight gain.