One of the earliest sources of mathematical input arises in dyadic parent–child interactions. However, the emphasis has been on parental input only in speech and how input varies across different environmental and child-specific factors remains largely unexplored. Here, we investigated the relationship among parental math input modality and type, children’s gestational status (being preterm vs. full-term born), and vocabulary development. Using book-reading as a medium for parental math input in dyadic interaction, we coded specific math input elicited by Turkish-speaking parents and their 26-month-old children (N = 58, 24 preterms) for speech-only and multimodal (speech and gestures combined) input. Results showed that multimodal math input, as opposed to speech-only math input, was uniquely associated with gestational status, expressive vocabulary, and the interaction between the two. Full-term children with lower expressive vocabulary scores received more multimodal input compared to their preterm peers. However, there was no association between expressive vocabulary and multimodal math input for preterm children. Moreover, cardinality was the most frequent type for both speech-only and multimodal input. These findings suggest that the specific type of multimodal math input can be produced as a function of children’s gestational status and vocabulary development.