Cognitive outcome in childhood of birth weight discordant monochorionic twins: the long-term effects of fetal growth restriction.

AIM: Intrauterine growth restriction (IUGR) is associated with poorer outcomes in later life. We used a monochorionic twin model with IUGR in one twin to determine its impact on growth and neurocognitive outcomes. METHODS: Monochorionic twins with ≥20% birth weight discordance born in the north of England were eligible. Cognitive function was assessed using the British Ability Scales. The Strength and Difficulties Questionnaire was used to identify behavioural problems. Auxological measurements were collected. Generalised estimating equations were used to determine the effects of birth weight on cognition. RESULTS: Fifty-one monochorionic twin pairs were assessed at a mean age of 6.3 years. Mean birth weight difference was 664 g at a mean gestation of 34.7 weeks. The lighter twin had a General Conceptual Ability (GCA) score that was three points lower (TwinL -105.4 vs TwinH -108.4, 95% CI -0.9 to -5.0), and there was a significant positive association (B 0.59) of within-pair birth weight differences and GCA scores. Mathematics and memory skills showed the largest differences. The lighter twin at school age was shorter (mean difference 2.1 cm±0.7) and lighter (mean difference 1.9 kg±0.6). Equal numbers of lighter and heavier twins were reported to have behavioural issues. CONCLUSIONS: In a monochorionic twin cohort, fetal growth restriction results in lower neurocognitive scores in early childhood, and there remain significant differences in size. Longer term follow-up will be required to determine whether growth or cognitive differences persist in later child or adulthood, and whether there are any associated longer term metabolic sequelae.

Catch-up growth and metabolic outcomes in adolescents born preterm.

BACKGROUND: Accelerated infant weight gain in individuals born full term is linked to cardiovascular risk in adulthood, but data in those born preterm are inconsistent. OBJECTIVE: To investigate the association between weight gain in infancy and childhood with later markers of the metabolic syndrome in adolescents who were born preterm. STUDY DESIGN: Longitudinal cohort study. SETTING: Children born preterm with regular assessments of infant growth had auxology, body composition (dual X-ray absorptiometry), blood pressure, insulin sensitivity and lipid profile determined in adolescence. RESULTS: We reviewed 153 children (mean gestation 30.8 weeks, median birth weight 1365 g) of whom 102 consented to venepuncture at a median age of 11.5 years. Adolescent height and weight standard deviation scores (SDS) were similar to population averages (0.01±0.92 and 0.3±1.2, respectively) and did not differ between infants when grouped according to degree of catch-up in weight gain in the immediate postdischarge period to 12 weeks of age. There were no significant associations between infant weight gain (change in weight SDS adjusted for length) and later metabolic outcome. However, there were strong associations between more rapid childhood weight gain (after 1 year of age) and subsequent body composition (higher fat mass %, fat mass index and waist circumference) and metabolic markers (higher fasting insulin, blood pressure and lower insulin sensitivity). CONCLUSIONS: The association of rapid weight gain on health is time critical in those born preterm; in early infancy, this does not impact on metabolic status in adolescence, in contrast to rapid weight gain in childhood, which should be discouraged. However, given the critical importance of brain growth in the neonatal period and infancy, further research is needed before strategies that discourage infant weight gain or catch-up can be recommended for infants born preterm.

Increasing Incidence, but Lack of Seasonality, of Elevated TSH Levels, on Newborn Screening, in the North of England.

Previous studies of congenital hypothyroidism have suggested an increasing incidence and seasonal variation in incidence, which may suggest nongenetic factors involved in aetiology. This study describes the incidence of elevated thyroid stimulating hormone (TSH) values in newborns, a surrogate for congenital hypothyroidism, measured as part of the screening programme for congenital hypothyroidism, over an eleven-year period (1994-2005), and assesses whether seasonal variation exists. All infants born in the Northern Region of England are screened by measuring levels of circulating TSH using a blood spot assay. Data on all 213 cases born from 1994 to 2005 inclusive were available. Annual incidence increased significantly from 37 per 100,000 in 1994 to a peak of 92.8 per 100,000 in 2003. There was no evidence of seasonal variation in incidence. The reasons for the increasing incidence are unclear, but do not appear to involve increasing exposure to seasonally varying factors or changes in measurements methods.

TSH levels in relation to gestation, birth weight and sex.

AIMS: Low birth weight is associated with hypothyroidism and an adverse metabolic profile in later life. Our aim was to examine the relationship between neonatal TSH and birth weight, gestational age and sex. METHODS: We compared blood spot filter paper TSH levels with birth weight, gestational age and sex in a 10% sample of infants screened for congenital hypothyroidism at a single centre in Northern England. All gestational ages were included with infants suspected of having congenital hypothyroidism excluded. RESULTS: Data on 1,728 male and 1,662 female infants were analysed. The distribution of TSH was significantly different between males and females, with males having a higher median TSH (0.7 vs. 0.6). Correlations were shown between TSH and birth weight (rho = -0.07, p = 0.0001) and gestational age (rho = -0.05, p = 0.008), with the birth weight association remaining independent of gestational age. The functional form of the model suggested that higher TSH in the lowest birth weight categories was responsible for the association between TSH and birth weight. CONCLUSIONS: Low birth weight is related to neonatal TSH levels. Further research is required to assess whether this association explains the relationship between higher TSH and an adverse metabolic profile in later life.