[Follow-up study of extremely low birth weight preterm infants to preschool age in the light of perinatal complications].

Introduction: Owing to the rapid progress of the medical science and technology, the chances of survival of the extremely low birth weight (<1000 g) preterm babies have dramatically improved. Nevertheless, the research findings on their long-term developmental outcome are inconsistent.

Aim: Our study has attempted to contribute to the understanding of the developmental mechanisms in the extremely low birth weight preterm infants and to the prediction of the developmental outcomes taking into account of the risk factors of development.

Method: 34 preterm children who were free of any major central nervous system injury were followed up from one to 5-6 years of age. The psychomotor development of the infants was assessed at 1 and 2 years of age and, at 5-6 years of age, intelligence tests were administered to the children. Perinatal and environmental factors were included in the data analysis.

Results: The extremely low birth weight preterm children as a group displayed no developmental delay at any of the measurement points. The mean developmental quotients were 98.6 and 106.6 at ages 1 and 2 years, respectively. At 5-6 years of age, the mean verbal IQ was 101.4, while the mean performance IQ was 92.9. Behind the group means there was a wide range of individual variations. The most powerful contributors to the developmental outcomes were birth weight, bronchopulmonary dysplasia, intra-uterine growth retardation, gender, and maternal education. The girls had a significant advantage over the boys in language development. Verbal intelligence was hampered by intracranial hemorrhage, while intrauterine growth restriction had a similar effect on the performance IQ.

Conclusions: Our results suggest that even the extremely preterm infants may have rather good chances of satisfactory mental development. However, the individual developmental prospects are influenced by a great number of domain-specific risk- and protective factors. Although at a group-level, infant psychomotor development is a significant predictor of later intelligence quotient, the rate of development may change at any age. The phenomenon of "moving risk" underscores the importance of the long-term follow-up of preterm infants. Orv Hetil. 2018; 159(41): 1672-1679.