"We have three separate services - too many," said association chairwoman Lynne Brice.
As well as the teen parent schools funded by the Education Ministry, the Social Development Ministry funds "teen parent intensive case workers" in 18 high-need locations and "youth coaches" for 1174 teenage parents receiving young parent payments. The other 2700-odd teenage parents are supported by family members or partners, or are in paid work.
The association says a single integrated service could provide social work support, organise work experience and apprenticeships, and host events for new parents to swap notes about their babies, as well as educating parents and their children.
"Early childhood education and secondary teachers visit homes and/or connect with learners through digital media," its proposal says.
Ms Brice said social workers were needed because many teenage parents left the school within months because of issues such as poverty, insecure housing, family and relationship breakdowns.
Teenage fathers also needed support, yet the teen parent schools were allowed to take only one "primary caregiver" for each child.
Teen parent schools have expanded from 18 units with 392 students in 2006 to 23 units with 492 students last year.
Unit 'like a second parent' to student with 3-year-old
Taonga Teen Parent Unit has become like "a second parent" for 19-year-old mother Shamayne Ashworth.
At James Cook High School in Manurewa, she began to "hang out with friends" when she was supposed to be at school.
She became pregnant at 15. "Once I found out I was pregnant, it changed me a bit."
The school found out a month before her daughter Deizharna was born, and referred her to Taonga, which is officially hosted by James Cook, because its classrooms and early childhood centre are 2.7km away in Palmers Rd.
The unit has a waiting list - social worker Tania Sigglekow-Leaf says there are always at least five in the queue. Ms Ashworth started in February 2012 when Deizharna was 5 months.
"They helped me with toilet-training her, getting her off the bottle, all her milestones. It's like they are a second parent," Ms Ashworth said.
She passed NCEA levels one and two and gained some level three credits. She studied hospitality.
"They helped me get on to a course at MIT [Manukau Institute of Technology] with a scholarship," she said.
After finishing the MIT course, she was hired as a receptionist and is now studying part-time to be a youth worker.