Why has the age of toilet training been pushed back in recent years?

What will be an ideal response?

In 1957, most children were toilet trained by 18-months of age. Since then, pediatricians put the message out that there was little reason to require it so early, so parents have started pushing back. Parents have also become more concerned (and thus, focused on) children's psychological development. Also, two technologies have contributed to the age of toilet training being pushed back: the disposable diaper and the washing machine. These technologies make it easier for parents to deal with children who are not toilet trained.