Trajectories of behavioral problems among moderate-late preterm children from 4 to 10 years: A prospective population-based study
Introduction
Each year, around one in every 10 babies worldwide is born preterm (<37 weeks' gestation) [1]. Preterm children are known to have more behavioral problems in later life than their healthy-term peers [2]. However, it is difficult to confirm that these problems also affect children born in the period near to term, from 32 to <37 weeks of gestation (i.e., moderate to late preterm; MLP), and not primarily children at the extreme end of the preterm birth continuum (<32 weeks' gestation). While MLP births represent up to 85% of all preterm deliveries [3], most follow-up research has been directed towards very or extremely preterm children (VPT; <32 weeks' gestation). Moreover, studies including MLP often combine them with VPT and/or do not formally compare them with full-term (FT) children in order to determine if these children are more developmentally at risk than FT peers [4,5]. Internalizing and externalizing behavioral problems are known to have deleterious consequences on various aspects of child life and they are likely to be persistent across time among FT and preterm children [6,7]. Thus, it is crucial to determine if MLP children are at a greater risk of developing these problems compared to FT peers across time.
A growing body of studies suggests that behavioral problems are not limited to children born VPT [8]. However, results are inconsistent. Some studies have found that behavior problems are more prevalent among MLP children compared to FT children [9,10], while others reported small or no differences between MLP and FT children [11,12]. Most of these studies had several limitations such as small sample size, reliance on transversal or retrospective designs, and the investigation of child outcomes at a broad range of developmental stages. In fact, a limited number of studies have followed MLP children over time using a prospective longitudinal design with repeated measures [10,11,13]. Due to this dearth of research, there is a limited understanding of the developmental trajectories of these children across time and the course and persistence of behavioral problems in this population.
The current longitudinal study addresses these limitations using data from a large population-based birth cohort of children from Canada. This study aims to examine the relation between MLP birth status and the overall developmental trajectory of multiple behavioral problems (hyperactivity-impulsivity, inattention, anxiety-depression, and aggression) measured repeatedly from ages 4 to 10 years using reports from the children's primary caregivers and teachers.
Section snippets
Sample
This study is part of the Quebec Longitudinal Study of Child Development (QLSCD), a Canadian representative population-based study of children's growth and development. This longitudinal study uses repeated multi-informant measures of child development across childhood, allowing for a distinctive insight into growth curves of behavioral problems among MLP children. This representative sample was drawn from the province's birth registry and used a stratified procedure based on living area and
Sample characteristics and descriptive statistics
The rate of MLP births in this study was about 5%, which was expected considering the rate of singleton prematurity in Canada (around 6%) [23], the rate of extremely and very preterm birth in Quebec (1.5%) and the rate of MLP births in Quebec (around 5.5%) [24]. Governmental statistics for singleton MLP births are, however, not available for Quebec or Canada. A total of 1841 children born FT and 89 children born MLP were included in the final sample. Table 1 presents the sample characteristics
Discussion
This population-based cohort study was the first to examine the relation between MLP birth and the longitudinal trajectories of multiple behavioral problems measured repeatedly from 4 to 10 years of age in a representative Canadian sample. According to the primary caregiver, MLP children were more likely to exhibit hyperactivity-impulsivity compared to their FT peers between 4 and 8 years. While persistent across time, the effect size of MLP birth regarding parent-reported hyperactive-impulsive
Acknowledgement
This project was supported by grants from the Ministère de la Famille, the Ministère de l'Éducation et de l'Enseignement supérieur, the Fondation Lucie et André Chagnon, the Institut de recherche Robert-Sauvé en santé et en sécurité du travail, the Centre hospitalier universitaire Sainte-Justine and the Institut de la statistique du Québec, all of whom conducted the Québec Longitudinal Study of Child Development (QLSCD). Michel Boivin is supported by the Canada Research Chairs (Tier 1) program.
Declaration of competing interest
None.
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