I think it is saddening to have their young lives thrown away into parenthood but that doesn't necessarily mean they are bad parents.
I think it is sad because they have a lot to experience about our world like college graduation and job hunting but now they are already thinking about parenting or children. It is life threatening for these teenage parents because they hold no diplomas/degrees to apply for work and most of the time are always considered for contract of service jobs though some continued their education to get degrees but imagine the year/s gone by the time they considered studying again to get a decent job. For most people, the problem will always be, “what am I going to feed my child/children? What is she/he going to feed his/her child/children?”
On second thought, those with fewer “parent-child” age gaps are usually closer with their child/children because the parent gets to cope with the child's thoughts better. They rarely lecture about "In our time.." stuff and easily grasps the new stuff that kids talk about these days.
So what am I really talking about?
I believe that teenage parents are not generally considered bad parents, only when they commit certain parenting mistakes like going to a party and leaving their babies behind with an all-nighter nanny.
When we talk about bad parenting, it's when a parent doesn't give proper nutrition to their children, doesn't earn money for their child's future, doesn't teach their child manners, hurts their child physically and mentally, doesn't respect their child's opinion or hear them out and many more. I believe then that teenage or not, once a parent does these hurtful things to their children, it is considered becoming a ‘bad parent’.
In the end, bad parenting is never about being a teenage parent it's when they fail to fulfill their jobs as the parent.