Babies impose a heavy burden on teenage girls. They have neither experience, money, nor time, and furthermore are still at an age where they need to be learning. In order to continue their education, the baby must be cared for by parents. That is, if they can survive the social stigma. In the end, many girls with children drop out of school or don’t attend a college. An unplanned new member of the household is problematic for financial reasons. Children can grow up in depravity or not properly cared for.
For boys, the burden is much less. They neither bear the baby, give birth, and many times they will refuse to stick around and the baby will grow up with an absentee father. Most of the consequences don’t involve much more than stress.