in the very early stages of development
Used other than figuratively or idiomatically: wearing a diaper, or needing to wear diapers.
Source: en.wiktionary.orgKeeping children in diapers beyond infancy can be controversial, with family psychologist John Rosemond claiming it is a "slap to the intelligence of a human being that one would allow baby to continue soiling and wetting himself past age two." Source: Internet
Detainees were clad only in diapers and not allowed to feed themselves. Source: Internet
I haven no idea what I'm in for because my kid's still in diapers and, from the looks of the increasingly bigger sizes, he might technically never outgrow them. Source: Internet
Let’s just say I had a bucket load of explaining to do to Kay and Ray Howard, my extremely Catholic parents, when I landed on their swank new doorstep with Laura and Vivs both still in diapers. Source: Internet
While her son, Will, was in diapers as a one-year-old, her daughter Eden, who had spent time with a foster family, had been started on elimination training before her first birthday. Source: Internet
In 2007, when the iPhone was introduced, the oldest millennials were freshly out of college, and the youngest of them were still in diapers. Source: Internet