If news is to be believed, parents will soon be able to tell a lot from their baby's pee - or the nappy will be able to tell a lot. Nappies have been developed in the US, likely to go into testing this year, with patches on the front that will change colour depending on the contents of the pee.  They should be able to detect UTIs, kidney dysfunctions and dehydration. A smartphone app will be able to send data directly to your GP. 

Very early days but an interesting new product in the making. I think it makes one less thing to worry about.  Although in the US they are estimating it will be 30-40% higher in cost.