A. G. Van Wassenaer

Thyroid function in very preterm infants: influences of gestational age and disease

It is not known how immaturity and disease influence postnatal thyroid function in infants <30 wk of gestational age. We performed serial measurements of plasma thyroxine (T4), free T4 (FT4), triiodothyronine (T3), reverse T3 (rT3), TSH, and T4-binding globulin (TBG) in 100 infants of <30 wk of gestation, during the first 8 postnatal weeks, to investigate the influences of disease and gestational age on the time course of thyroid hormones. One hundred infants were divided twice into two groups: 1) in a group of 25-28 and of 28-30 wk of gestation; and 2) in a sick and a healthy group, with similar gestational ages. The time course of T4, FT4, T3, TSH, and TBG, but not rT3 differed significantly (p < 0.005) between the gestational age groups. T4 and FT4 decreased to levels below the cord blood value with a deeper FT4 nadir on d 7 in the youngest group. Disease decreased T4, FT4, T3, TSH, and TBG concentrations especially during the 1st wk after birth (p < 0.005). However, the FT4 nadir on d 7 was similar in sick and healthy infants. After 3 wk, T4, FT4, T3, and TBG were higher in the sick group compared with the healthy group. rT3 levels were not increased in sick infants. We conclude that the extent of the FT4 decrease after birth in infants of <30 wk gestation is mainly influenced by gestational age and probably reflects a transient depletion of thyroidal hormone reserves. rT3 cannot be used as a marker of nonthyroidal illness in very preterm infants.

Thyroxine administration to infants of less than 30 weeks gestational age decreases plasma tri-iodothyronine concentrations

OBJECTIVE To investigate the effect on thyroid hormone metabolism of the administration of thyroxine to very preterm infants. DESIGN AND METHODS Two hundred infants of less than 30 weeks gestation were enrolled into a randomized, double-blind, placebo-controlled trial. Thyroxine (T4) (at a fixed daily dose of 8 microg/kg birthweight) or placebo was started 12-24h after birth and discontinued 6 weeks later. Plasma concentrations of T4, tri-iodothyronine (T3), reverse T3 (rT3), TSH, and thyroxine-binding globulin were measured weekly during trial medication and 2 weeks thereafter. RESULTS The T4 and the placebo group each comprised 100 infants. Antenatal, perinatal, and postnatal clinical characteristics were comparable in both groups. T4 and rT3 were significantly increased in the T4 group. TSH concentrations were depressed in the T4 group and T3 was significantly decreased, probably as a result of TSH depression. The T4/T3 and T4/rT3 ratios differed significantly between the two study groups. CONCLUSIONS Daily T4 administration during the first 6 weeks after birth to infants of less than 30 weeks gestation prevents hypothyroxinemia, but decreases plasma T3 concentrations. Our finding possibly implies that very preterm infants should receive supplements of both T4 and T3.

Long-term follow up of children exposed in utero to nifedipine or ritodrine for the management of preterm labour

Objective  To compare the long‐term psychosocial and motor effects on children exposed in utero to nifedipine or ritodrine for the management of preterm labour.

Reliability, sensitivity and responsiveness of the Infant Behavioral Assessment in very preterm infants.

Aim:  The aim of this study is to investigate the reliability, sensitivity and responsiveness of the Infant Behavioral Assessment (IBA) to evaluate neurobehavioural organization in very preterm infants.

446 High Frequency of Low Severity Disabilities in Very Premature Infants at Age Five

Background: Children born preterm run an increased risk of problems on multiple domains. The co-existence of these problems needs more attention. Aim: To find out how may preterm born children have disabilities in comparison with term controls. Methods: Children (N = 127) born at -1SD below mean were defined as disability. Results: 104 preterm born children (mean GA 28.8 weeks (SD 1.6), mean BW 1043 grams (SD 250)) and 91 term controls (mean GA 39.8 weeks (SD 1.8), mean BW 3224 (SD 528) participated. In the preterm group, 50% had one or more abnormal IQ score and 44% had minor neurological dysfunction, while 5% had CP. In the term controls this was 22%, 7% and 0% respectively. In the preterm group, 75% had ≥1 disability and 52% ≥2 disability and this was 27 resp. 10% in the term controls. Conclusions: Of very premature children, able to undergo an age appropriate IQ test, only 25 % compared to 73% of term controls is without disability on all domains.

447 Parental Education Does Not Influence Outcome of Very Preterm Children on All Developmental Domains

Background: Children born preterm run an increased risk of problems on multiple domains. It is not clear how SES influences these different outcomes. Aims: To study the relation between parental education and multiple domain outcomes at age five in very preterm born children in comparison with term controls. Methods: 104 children born < 30 weeks infants GA and/or < 1000 gr at birth and 95 term controls were assessed at the (corrected) age of five years. Motor, neurological cognitive (total, verbal and performal IQ, and processing speed quotient) and behavioural funtioning were assessed using the M-ABC II, the Touwen examination, the WPPSIIII- NL, and the SDQ. (parents and teachers). The differences between preterm and term children were studied in three strata of parental education level (high, medium, low). Results: The mean difference in IQ score between 104 preterm and 95 term children was 10 points. In the high education stratum this difference was 5 compared to 14 in the low stratum. The same pattern was found for verbal, performal IQ, processing speed and SDQ scores. Neurological outcome of preterm born children was not normal in 49% especially due to minor neurological dysfunction (MND), which occurred in 44%. MND nor M ABC scores were influenced by parental education, with comparable preterm-term diferences in each parental education stratum. Conclusions: The biological risk of preterm children is highlighted by their neurological outcome. The social risk factor modifies this biological risk and determines especially cognitive and behavioral outcome.