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The influence of birthweight for gestational age on neurodevelopmental outcome at 1 year of age in premature infants weighing <1000gms

Presented at the Neonatal Society 2005 Summer Meeting (programme).

Lloyd J1, Riley K2, Wyatt J2, Peebles D1

1 Department of Obstetrics & Gynaecology, 86-96 Chenies Mews, UCL, London WC1E 6HX, UK
2 Department of Paediatrics, UCL, London WC1E 6HX, UK

Background: Premature infants are at increased risk of developing cerebral palsy and other neurological problems, such as cognitive and behavioural problems (1). Materno-fetal infection/inflammation has been implicated, both as a cause of preterm labour, and perinatal brain injury (2). By contrast, the role of fetal growth restriction in impairing brain development remains unclear, with a poor long-term neurodevelopmental outcome reported in some studies (3) but not in others (4).

Aims: To investigate the association between intrauterine growth restriction, as well as other known risk factors, and neurodevelopmental outcome in a cohort of premature infants at a single tertiary centre.

Methods: 220 premature infants with a birthweight ≤1000g cared for at University College Hospital London from 1995 to 2001, were prospectively followed up at a corrected age of 1 year using a validated neurodevelopmental assessment tool, the Griffiths Mental Development Scales. Birthweight was classified as <2nd, 2nd to 9th and ≥10th centile and z-scores calculated (the number of standard deviations from the mean birthweight for gestational age) using neonatal birthweight charts derived from a similar population. Histological evidence of placental infarction or chorioamnionitis and ultrasound evidence of brain lesions (cystic periventricular leucomalacia [PVL] or ventricular dilatation >2SD) were also recorded. A multivariate analysis of risk factors was performed, adjusting for z-score and gestational age. Ethical approval was obtained from joint UCL / UCH ethics committee.

Results: 55 of the initial cohort of 291 babies died within the first year; of the remaining 236, 220 had a Griffiths developmental quotient (GQ) recorded (93.2% follow up). On univariate analysis, babies with a birthweight <2nd centile had a lower mean GQ score than those with a birthweight ≥10th centile (82.7818.85 versus 95.3116.54, p<0.001). The presence of cystic PVL or ventricular dilatation was associated with a lower mean GQ score of 72.5023.13 versus 97.2014.98 (p<0.001) and 86.5420.44 versus 98.0914.84 (p<0.001) respectively. There was no association between histological chorioamnionitis and GQ score. These findings were confirmed by multivariate analysis with a significant association between lower Z-score, gestational age, male gender, the presence of cystic PVL or ventricular dilatation and lower GQ score. In the multivariate model an increase in z-score of 1.0 was associated with an increase in GQ score of 5.61.48 points; similarly, an increase of 1 week in gestational age increased GQ by 2.10.71 points.

Conclusions: Growth restriction, extreme prematurity and major cranial ultrasound abnormalities have a significant negative association with neurodevelopmental outcome in premature infants at 1 year of corrected age.

1. Hagberg B, Hagberg G, Beckung E, Uvebrant P. Acta Paediatr 2001; 90(3):271-277
2. Dammann O, Leviton A. Pediatr Res 1997; 42(1):1-8.
3. Sung IK, Vohr B, Oh W. J Pediatr 1993; 123(4):618-624
4. Gortner L, van Husen M, Thyen U, Gembruch U, Friedrich HJ, Landmann E. Eur J Obstet Gynecol Reprod Biol 2003; 110 Suppl 1:S93-S97.

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