¿Cuando vas a dar a luz?

¿Cuando vas a dar a luz?
When are you going to give to the light?

Clearly a literal translation doesn't work here. So what does this mean?  Let me say it a different way:

¿Cuándo va a nacer el bebé?

Literally, "when is the baby going to be born", but a more natural translation would be "when is the baby due".  And that's exactly what our our phrase "dar a luz" means.

¿Cuando vas a dar a luz?
When are you going to have the baby?

There's another verb that's used to talk about giving birth, parir. 

Mi esposa va a parir
My wife is going to have the baby

However, ten cuidado (be careful) with this one.  Many spanish speakers reserve parir for talking about animal births.  It all depends on the country and the region, so I suggest you reserve this one for animals and use the other more standard options.

There's also another very common way to ask someone when their baby is due.

¿Para cuándo esperas?
When are you due?

You could also shorten this to:

¿Para cuándo?

Babies are always fun to talk about, and these phrases are great conversation starters, not to mention just being able to better communicate with your Spanish speaking friends. 

¡Hasta pronto!