What is the role of good dental care during pregnancy?

Is it because the baby also uses up the mother's calcium?
--------------------
Good dental care is something to have regardless if you are pregnant or not, but especially during pregnancy because yes, the baby takes away from the calcium the mother is used to getting as well as other nutrients and bad dental care during life and pregnancy could cause weak teeth and chips as well as sensitive gums which could cause bleeding even at the slightest brush. Good dental care also reduces morning sickness, or so I've known.
Source