Ms Riley, who's in her 30s, says inspiration for the study was drawn from her own encounters as a child-free woman.
"I often found that when you were with a bunch of women together and passing a baby around, and you weren't participating in all of the gooing and gaaing, you would get this, 'what's wrong with you?'
"My feeling was, no offence, but I'm not interested in your baby. Why does that have to be such a problem?
"Once I considered it, I thought, what is going on here? Am I just odd? But once I got on to it, I found there is a group who thinks not everyone has to have kids - but society still doesn't accept that."
A Statistics New Zealand report predicted one in seven of people born around 1965 would not have children, and one in three would have at least one child who would themselves be childless.
Ms Riley estimated the childless rate among New Zealand women was 10 per cent, although many of these were unable to have children and available data did not make a distinction between the two groups.
Her study has also convinced her that expectations and needs for couples to have children were driven by factors that were social rather than biological.
"There's this expectation that you'll love a baby, you'll love being pregnant, it'll mean so much and you'll never look back - we still see parenthood and having kids with rose-tinted glasses."
The couples who took part in her study said they frequently encountered negative perceptions at work and at social functions.
Common judgments were that the couples cared only about money, themselves and their jobs.
She was pleased her book had helped child-free couples to realise they were not alone.
"Just because we don't want kids doesn't mean we hate them."