That's the first question we have for Spanish researchers that played mum's voice to an unborn baby by putting a little speaker in her vagina.
The results showed babies reacted excitedly to mum's voice booming from the other side of the uterus with facial expressions and movements. How exciting.
But still. Why?
Here's another question: how exactly does this happen?
Well the answer, it seems, is to promote a tampon-sized speaker that can connect to a phone called Babypod.
Once inserted, parents can use Babypod to give their little one a call and have a chat about, I don't know, the weather. How are things down there?
Private medical institution Institut Marquès scientific director Álex García-Faura said the study showed babies reacted more strongly to vagina-transmitted sounds than through the abdomen and voice reactions were different to music.
"The response is different when we emit music and we put this down to music and voice activating different brain circuits: music activates neuronal circuits that trigger emotions," García-Faura said.
"This leads us to a new question: to learn whether the hundreds of babies that you have already stimulated during pregnancy will be able to recognise their parents' voices if they have heard them during pregnancy from within the womb and also to find out whether this represents a stimulus for language and communication development."
Or, you could just wait until the baby is born to say 'hello'.
Your call, parents, your call.