No Association Between Transient Hypothyroxinemia of Prematurity and Neurodevelopmental Outcome in Young Adulthood.

CONTEXT

Transient hypothyroxinemia of prematurity (THoP) has been associated with neurodevelopmental impairment in infancy and childhood. It is not known whether these relations persist into adulthood.

OBJECTIVE

The objective was to examine whether there is an effect of THoP on intelligence quotient (IQ) score and motor functioning at a young adult age.

DESIGN

This study was part of the 19-year follow-up of the Project On Preterm and Small-for-gestational-age birth (POPS) cohort, which included infants born very preterm (ie, <32 wk) and/or with a very low birth weight (ie, <1500 g).

SETTING

This was a multicenter study.

PATIENTS

There were 398 19-year-old participants of the POPS cohort, of whom 120 had THoP.

EXPOSURE

T4 concentrations were obtained through the national neonatal screening program for congenital hypothyroidism. THoP was defined as a total T4 concentration < -3 SD of the daily mean (approximately 60 nmol/L).

MAIN OUTCOME MEASURES

Main outcome measures were IQ and motor functioning, measured with the digital Multicultural Capacities Test-Intermediate Level and a revised version of Touwen's examination of minor neurological dysfunction, respectively.

RESULTS

THoP was not associated with IQ score (mean difference, 0 [95% confidence interval, -3.8 to 3.8] points) or motor function (mean difference, 0.6 [95% confidence interval, -1.3 to 2.5] points) after adjustment for demographic and perinatal characteristics.

CONCLUSIONS

No associations between THoP and neurodevelopmental outcome at age 19 years were found.