Most cottons shrink mostly in one direction. Although I would not bet ahead of time whether it will be crosswise or lengthwise.
A very few do shrink in both directions.
I measured hundreds of pieces before and after washing them - I started to measure after I was going to sell a piece of cat print - that I know was over 36 inches long when I purchased it - and it was only 35 inches long when I was going to sell it.
I remeasure all the fabric I buy when I get it home, too. I won't fuss if it is cut to the thread for length - but I am annoyed if it is cut crooked or short.