Clothing sizes update

I no longer feel like petitioning the children's clothing industry to change their sizing. C must have had a growth spurt since the last time I tried her 18 m pants on. Today she got to wear pants that fit! They were labeled 18 m. and they stayed on! So, she now wears 18 month pants, 18 month shirts, and 24 month dresses? How much sense does that make?