The Cyfle unit in Wrexham provides tuition from the 28th week of pregnancy and continues for a term-and-a-half with the provision of a creche.
A recent inspection by Welsh agency Estyn found that the unit was "well managed and organised" so that pregnant or parenting schoolgirls had the "best possible opportunity" to continue their education.
Reintegration is the main aim of the unit, allowing young mums to pursue their studies during the early months of parenthood, and helping them to return to mainstream school with as little disruption as possible.
"The quality of teaching at the centre is outstanding," said inspectors.
"Teachers work as a team to make best use of their expertise in supporting pupils in their studies."
As well as following a core curriculum for GCSE and other accredited courses, pupils also make "outstanding" progress in developing their personal and social skills.
"Pupils are very productive, make up for lost time and often achieve levels of accreditation that exceed expectation," said Estyn.
"They become increasingly confident and well motivated through achievement, boosting self-esteem."
The unit was awarded the top grade in each of the seven categories including the effectiveness of the teaching, how well pupils are cared for and the efficiency of the management in using resources. Teacher-in-charge Teresa Foster Evans said facilities like Cyfle prevented many young women from "dropping off the educational ladder".
"I think it works because of the small numbers and the expectations we place on them, which shows them that we believe they are worth it," she said.
Last year, according to Estyn, some pupils were successful in gaining GCSE passes in up to nine subjects. Mrs Foster Evans says within 18 months, two-thirds also go on to some form of further education and training.
Estyn said there was still too little opportunity for girls to gain experience in the world of work, but Cyfle says this is already being addressed, with representatives from professions being invited in to discuss careers with the pupils.