While much about the process of diapers and how they go on and off hasn't changed since our son Grant was in diapers, quite a bit about the actual design and functionality of diapers has.
We were fortunate enough to get several packages of diapers from family and friends even before the girls were born. The majority of them were the Pampers Swaddlers brand and style. I've already lost track of how many we have gone through in the first month, but it is well into the 100's and probably closer to 1000.
I didn't realize it until after several diaper changes, but a little blue line was present down the front of the diapers. Apparently this is some sort of wetness indicator, and allows me, the diaper changer, to know if the wearer has a wet diaper without going through the hassle of removing it. Brilliant!
However, after I began to think about this, I can see this was just a ploy by the diaper companies to get me to use more and more diapers. My wife, would see the blue line and say: "Oops, time to change your diaper".
In the past, you might not notice if they had a little tinkle hear and there and it might save you 1 or 2 diapers on any given day. Now...you see the blue line, on goes a new diaper...times two for us.
MISSION ACCOMPLISHED - Proctor & Gamble!
I am sure that little blue line is the most wetness sensitive piece of plastic/fabric on the planet.