How common was, what we now consider "child marriage" among medieval peasants in western and central europe?

As recent events unraveled. I had a brief convo with my friends in our WhatsApp group about child marriage. I saw that it was common among nobility, but my source was just a random guy on a forum. While my friend said that it was common in the peasantry, too. And even some of my common native vocabulary (Czech) comes from child marriage. Now again, the source is literally "my friend told me," so I wanna run it by someone more qualified.