Can a mother give birth to baby before getting married?

Again, together with small kids, we entered into an interesting conversation. 

There was hot debate on "having a baby"~ "The couple will only have baby after they get married." Someone came out with this topic suddenly. (Yes, quite true)"So why did mother of some children give birth first before they got married?" (Oh Veronica! How can I bring the right value in and at the same time, not being judgemental?!)
"Tell me, jie jie (sister in english), tell me! Can a mother give birth to a baby if she hasn't got married?" (Technically, yes....oh, are they ready for this? How can I explain to them? )
"Yes..." (As a science student, I'm not going to lie on this)
"Huh....? Can meh?"
"Yes....Mother Mary!" (Finally, I found a role model)
You may think that they might behave skeptical towards Mother Mary and her virginity.....
"Haiya, that's because Mother Mary was BLESSED by GOD!!" They replied. So I say, KIDS KNOW BEST!
And I replied to conclude it asap, "So every mother who has been blessed will have her children!"

Thanks God for you've revealed the Kingdom of Yours to mere children.