Prematurity linked to speech sound differences from infancy into school years, review finds

A review of 28 studies across 14 countries finds that children born before 37 weeks often follow a different speech sound development trajectory, strengthening the case for monitoring beyond infancy.

A scoping review by Burr and colleagues has found that children born before 37 weeks’ gestation often show differences in speech sound development when compared with full-term peers, with most of the evidence pointing in the same direction across infancy, preschool age and the early school years. The review covered 28 studies from 14 countries and reported that 25 of them found speech-related differences between preterm and full-term children from three months to 12 years of age. The pattern suggests that prematurity can affect speech acquisition in several ways, although the size and nature of the gap varied from study to study.

The evidence base spans a wide range of methods, from infant vocalisation recordings to formal articulation tests and parent interviews. Early work by Brown and colleagues in the United States found that both healthy preterm infants and those who had suffered perinatal injury showed delays in speech sound development, but the group with intraventricular haemorrhage was more affected and showed greater variation in performance. In Italy, D’Odorico and colleagues later reported that preterm children differed from full-term children in aspects of early phonetic and phonological growth, particularly by 18 months, when babbling complexity and consonant development began to diverge.

Several studies in the review suggest that the differences can persist well beyond the toddler years. In Switzerland, Largo and colleagues found more articulation problems among preterm children at age five, with boys generally more affected than girls, and noted that children who were slow to develop language early on were more likely to have articulation difficulties later. In Sweden, Jennische and Sedin reported lower scores in speech motor function and sound pattern measures at 6.5 years among preterm children, while a companion parent interview study found later babbling and delayed intelligible speech in the preterm group.

The review also points to a possible dose-response relationship, where greater prematurity or additional medical complications are associated with poorer speech outcomes. A study from Australia found more speech difficulties in preterm children on a screening assessment than in the term-born comparison group. In Canada, Rvachew and colleagues observed that very preterm children could reach a level of canonical babbling similar to full-term infants by 18 months, but they tended to lag earlier on. More recent work in Australia, Brazil, Finland, Iran, the Netherlands and the UK has continued to report differences in phonology, intelligibility, oral-motor control and neurodevelopmental follow-up, with some children showing catch-up and others remaining at risk. The review’s broad conclusion is not that every preterm child will have speech problems, but that the group as a whole warrants closer monitoring so that difficulties are recognised before they become entrenched.