There are many different factors that can contribute to a child wetting the bed. It certainly does not mean that something is wrong with the child. On the contrary, approximately five million children in the United States wet the bed. The majority of the time it is not a medical issue; however, if the night time accidents continue to occur or suddenly begin after being fully trained it is best to consult with your pediatrician. A child should never be made to feel bad for wetting the bed. Let them know they are not alone. Be pro-active. Provide plastic lining for their beds, remind them to go to the bathroom before they go to bed, and limit their liquids as their bed time approaches.
Source Article: https://www.healthychildren.org/English/ages-stages/toddler/toilet-training/Pages/Bedwetting.aspx