The Duke and Duchess of Cambridge are on what's called Team Green. As revealed in 7 reasons not to find out your baby's gender this term describes "expectant parents who don't find out their baby's gender" prior to birth. Team Green, of course, distinguishes such people from members of Team Blue and Team Pink, those who know exactly which flavour baby they'll be taking home.
When I was pregnant, my baby kicked so hard I decided it had to be a boy; sometimes I even wondered if he had rugby boots on. So, having eschewed the tests to discover gender, the arrival of our baby daughter was a surprise. And, sure enough, prior to the birth we'd had her bedroom walls painted a pale (gender-neutral and predictable) mint green.
There's something quaint and old-fashioned about actually waiting to see whether your baby is a boy or a girl - or, rather, a prince or a princess if you're Will and Kate. With the rampant use of epidurals and the rise of C-sections and other interventions, this is one last facet of the birth process that can remain traditional, unaffected by progress and modern science. In such cases "It's a boy" and "It's a girl" are newsworthy statements rather than redundant phrases simply underscoring that which has already been established.
Many people relish the sense of anticipation that ensues from remaining ignorant in this regard. As the blogger at Baby Center wrote, not knowing "brings out the fortune teller in everyone ... the ridiculous gender-predicting games, the wives tales, the needle and thread and Chinese-chart games, the bump shape predictions, the morning sickness and heartburn analysis".
Women who elect to be informed are often given an indication of the baby's gender at the 20-week ultrasound. Yet that's not a definitive answer because "it's tough to get a 100% guarantee with ultrasound".