ABSTRACT. Background. Thyroid hormones are essential for brain development. We conducted a randomized, controlled trial with thyroxine (T4) supplementation in infants <30 weeks' gestation and with the last neurodevelopmental follow-up moment at the age of 5.5 years. T4 supplementation was associated with improved outcome of infants <28 weeks' gestation and worse outcome of infants of 29 weeks' gestation. We studied gestational age-dependent effects of T4 supplementation at the mean age of 10.5 years in children participating in our randomized, controlled trial.Methods. Questionnaires regarding school outcome, behavior, quality of life, motor problems, and parental stress were sent to the parents and children and their teachers at the same time point for all surviving children (9 -12 years of age).Results. Seventy-two percent of the families responded to our questionnaires. Nonrespondents had more sociodemographic risk factors and worse development until 5.5 years. At the mean age of 10.5 years, T4 supplementation was associated with better school outcome in those who were <27 weeks' gestation and better motor outcome in those who were <28 weeks' gestation, whereas the reverse was true for those who were born at 29 weeks' gestation. No other gestational age-dependent outcomes were found.Conclusions. Gestation-dependent effects of T4 supplementation remain stable over time. These effects do not prove beneficial effects of T4 in infants <28 weeks but should be the background for a new randomized, controlled trial with thyroid hormone in this age group.

Perinatal mortality or abnormal child development occurs in one third of pregnancies with early-onset and severe hypertensive complications and is highest in the lowest GA and BW ranges.

The aim of the present study was to evaluate whether the application of Dutch versus US test procedures and norms of the Bayley Scales of Infant Development - 2nd edition (BSID-II) leads to different developmental outcomes. The BSID-II was administered to 376 preterm infants (191 males, 185 females; mean gestational age 30wks [SD 2.7], mean birth-weight 1242g [SD 385]) at corrected ages of 6, 12, 24, and/or 36 months. Raw scores were calculated twice with US and Dutch test procedures. Raw scores as well as Mental Developmental Index (MDI) and Psychomotor Developmental Index (PDI) scores, calculated on the basis of Dutch versus US normative data, were compared. Small but statistically significant Dutch-US differences were found between raw scores. Large, clinically relevant Dutch-US differences were found for MDI and PDI scores, especially at 6 and 12 months. These differences were likely to have been caused by a bias in the Dutch normative data, although a slower developmental pace of Dutch children in general could also have a role. This study highlights the problems that can occur when using a test that was developed in another country, even when local standardization is available.