According to Rescorla (1989), a child may be identified as a late talker if, by the age of two, they can say fewer than 50 words or are not yet combining two words together (for example, "more milk" or "mummy come").

A large longitudinal study in the United States followed 9,600 children, collecting data when the children were 9 months, 2 years, 4 years, and 5 years old. The researchers identified eight risk factors associated with children who were classified as late talkers at age two (Hammer, Morgan, Farkas, Hillemeier, Bitetti, & Maczuga, 2017).

The eight risk factors linked to late talking are:

• Being a boy
• Lower socioeconomic status
• Being part of a multiple birth (e.g., twins or triplets)
• Having an older mother at the time of birth
• Lower birth weight (1500–2500 g)
• Less effective parenting practices
• Spending fewer than 10 hours per week in childcare
• Attention difficulties

It is important to remember that risk factors are not the same as causes. A risk factor simply means that the likelihood of a difficulty may be higher. It does not mean the problem will definitely occur.

The researchers also found that children identified as late talkers at age two were more likely to have a smaller vocabulary at age four and lower school readiness at age five.

For parents, some of these risk factors cannot be changed, such as a child's sex or birth weight. However, others are within your influence, such as your parenting and communication style. This means parents should never underestimate their impact. By talking, reading, and interacting with your child more intentionally, you can help reduce the likelihood of later language difficulties.

Early childhood educators also play an important role. Early vocabulary development forms an important foundation for later learning. Teachers can support this by incorporating vocabulary-building opportunities into lessons, daily routines, and play activities. If a child appears to have noticeably weaker vocabulary skills, early referral and support can make a meaningful difference.

Reference

Hammer, C. S., Morgan, P., Farkas, G., Hillemeier, M., Bitetti, D., & Maczuga, S. (2017). Late talkers: A population-based study of risk factors and school readiness consequences. Journal of Speech, Language, and Hearing Research, 60(3), 607–626.