Le retard de croissance intra-utérin et la grande prématurité : impact sur la mortalité et les morbidités à court et à moyen terme

Abstract : Background: Intrauterine growth restriction (IUGR) refers to the inability of the fetus to achieve its genetically determined growth potential due to various causes. Most often, it is defined by a birth weight less than the 10th percentile for gestational age using neonatal growth curves. This thesis aims to answer unresolved questions about the definition and consequences of IUGR in the context of very preterm birth: (1) what is the best definition of IUGR for identifying children at risk? (2) What are the risks of mortality and neonatal respiratory and neurological morbidity associated with IUGR and are there interactions with the underlying pregnancy complications responsible for the very preterm birth? (3) What is the impact of IUGR on neurodevelopmental at 2 years, especially for children born extremely preterm ? Methods: We used two data sources. The MOSAIC study (Models for Organising Access to Intensive Care for Very Preterm Babies in Europe) is a European population-based study that included all births occurring between 22 and 31 weeks of gestation in 2003 in ten European regions. The children were followed until hospital discharge (study population = 4525 infants). The second source is a cohort of children born before 27 weeks of GA who were hospitalized in the neonatal intensive care unit at the Port Royal Hospital from 1999 to 2008 and had a pediatric examination and Brunet-Lézine (BL) neurodevelopmental assessment at 2 years of corrected age (445 children in the cohort, 268children followed at 2 years). The BL assessment includes four areas of child development: gross motor, fine motor, language and social interaction skills. Results: In both populations, the risk of death and bronchopulmonary dysplasia were higher for children with a birth weight <10th percentile of neonatal growth curves but also for children with a higher birth weight (between the 10th and the 24th percentile of neonatal growth curves or <10th percentile of fetal growth curves). In contrast, there was no link between neurological complications and low birth weight and no interactions with pregnancy complications. IUGR was associated with neurocognitive delay among extremely preterm children evaluated at two years of corrected age, especially for fine motor and social interaction skills, but not for language and gross motor skills. We did not find any association between IUGR and the risk of cerebral palsy at two years of corrected age. Conclusions: The use of the 10th percentile of neonatal growth curves is not suitable for identifying the impact of IUGR in very preterm infants; using higher thresholds or fetal growth curves is necessary. IUGR increased the risks of mortality and bronchopulmonary dysplasia, but was not associated with severe brain damage; these associations are observed in multiple clinical contexts (vascular and infectious pregnancy complications, and births at very early gestational ages). IUGR is a risk factor for poor medium-term neuro-development. Our results raise new questions about the appropriate surveillance for children with IUGR after discharge from the hospital and also about possible biological mechanisms that could explain the relationship between IUGR and respiratory morbidity and neurocognitive development.
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Mayass El Ayoubi. Le retard de croissance intra-utérin et la grande prématurité : impact sur la mortalité et les morbidités à court et à moyen terme. Médecine humaine et pathologie. Université Sorbonne Paris Cité, 2015. Français. ⟨NNT : 2015USPCB139⟩. ⟨tel-01578095⟩

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