Propose a semi-supervised learning approach using unsupervised pretraining to improve the performance of your NLP model in this scenario. Explain the rationale behind your choice and potential tradeoffs.

Implement unsupervised pretraining on the unlabeled text corpus to inject prior knowledge into the model. This can help the model learn more robust representations, even with limited labeled data. However, be aware that over-reliance on pretraining may lead to under-exploitation of the available labeled examples.