Socio-demographic determinants of infant neurodevelopment at 18 months of age: Mother–Child Cohort (Rhea Study) in Crete, Greece

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Abstract

Studies on determinants affecting child development are still limited in Greece. The aim of the present study was to describe the socio-demographic characteristics associated with neurodevelopment in infants aged 18 months in the Mother–Child Cohort (Rhea Study) in Crete, Greece. A total of 599 (72.9%) mothers agreed to participate in the neurodevelopment protocol and 612 infants (586 singletons and 26 twins) were assessed by means of the Bayley Scales of Infant and Toddler Development (3rd edition). The present analysis includes 605 infants. Multivariable linear regression models were implemented to examine the associations between the Bayley-III standardised scores and different parental and infant characteristics, also adjusting for quality of assessment. Girls were found to have better neurodevelopmental outcomes in cognitive, receptive and expressive communication, fine motor and social-emotional development. Maternal higher education was positively associated to almost all aspects of infant neurodevelopment assessed. Increasing number of older siblings was negatively associated with cognitive development, communication skills and gross motor development. Our results, also, suggest a positive effect of maternal employment on infants’ receptive and expressive communication, and gross motor scores. The results of the present study suggest that in the population on Crete social and environmental factors contributed more to infants’ neurodevelopment at 18 months than biological factors.

Highlights

► We examine socio-demographic characteristics associated with infant neurodevelopment. ► 605 infants assessed by means of Bayley-III. ► Maternal higher education and being a girl were associated with high scores in nearly all scales. ► Maternal employment was positively related to infants’ communication and gross motor scores. ► Increasing number of older siblings was related to poorer neurodevelopment.

Introduction

Brain development starts antenatally and continues in childhood and adolescence. Biological, psychological and social factors have effects on this development (Epstein, 2001) during both pre-and postnatal periods (Stringari, Meotti, Souza, Santos, & Farina, 2006). The period of highest vulnerability of the human brain begins in the prenatal phase (O’Donnell, O’Connor, & Glover, 2009) and extends over many months through infancy into early childhood (Rice & Barone, 2000).

Neurodevelopmental and psychiatric disorders have their origins in very early brain development and distinct factors have been implicated in their aetiology (de Graaf-Peters and Hadders-Algra, 2006, Sonnander and Claesson, 1999). Biological factors including extreme prematurity, congenital defects, and other direct causes of brain injury are well-identified causes (Hollomon, Dobbins, & Scott, 1998). In addition, epidemiological research over the past two decades has indicated that in utero infections may confer a risk for neurodevelopmental disturbances, e.g. autism and global developmental delay (Arndt, Stodgell, & Rodier, 2005), and associated psychopathology, e.g. schizophrenia (Brown & Susser, 2002) in the offspring. During the past two decades, a growing body of studies has investigated the effects of early exposure to neurotoxic agents on cognitive and behavioral development in infancy and childhood (Grandjean & Landrigan, 2006).

Psychosocial factors may also adversely affect children's cognitive and social-emotional competence. Several studies have reported relationships between maternal stress/anxiety and depression and adverse infant developmental outcomes (Deave et al., 2008, Glover and O’Connor, 2002, Rice et al., 2010, To et al., 2004). Studies investigating direct effects between maternal socio-demographic determinants and children's neurobehavioral development are, however, limited. Socio-demographic characteristics, such as maternal age and education, have been related to child development. In particular, Chapman, Scott, and Mason (2002), examined the predictive value of maternal age and education in relation to rates of administratively defined mental retardation in a 3-year birth cohort (N = 267,277). The findings indicated that low maternal education and/or older maternal age were associated with increased risk of mental retardation. The study of Dollaghan et al. (1999), based on spontaneous language samples from 240 three-year-old children, showed statistically significant linear trends across maternal educational levels for measures of early speech and language. In addition, family socioeconomic status (SES) was found to be a powerful predictor of child development (Hoff, 2003).

The relative importance of risk factors may change during the early years of life, with biological factors becoming less important in time and psychosocial gaining influence. Although a single adverse biological and/or psychosocial marker does not necessarily lead to developmental delay, the simultaneous presence of several negative factors may lead to an increased risk of developmental disabilities (Garmezy, 1993). The identification of key factors may allow the identification of developmental problems earlier and prevent complications.

Studies on determinants affecting child development are limited in Greece (Papaligoura et al., 2004, Syrengelas et al., 2010). The aim of the present study is to describe the socio-demographic characteristics associated with neurodevelopment and to identify the determinants of neurodevelopmental outcomes in infants aged 18 months in Rhea cohort study, Crete, Greece. A number of social and demographic factors are explored in this paper as potential predictors of neurodevelopmental outcomes in infants aged 18 months. On the basis of the existing literature, we hypothesized that girls and first children in the family would have better neurodevelopmental outcomes than boys and children with older siblings (Cornish et al., 2005, Hops, 1995, Putnick et al., 2007), whereas social, environmental and biological factors such as advanced maternal age, low maternal education, smoking during pregnancy, low birth weight and prematurity would have a negative effect on infants’ neurodevelopment (Bhutta et al., 2002, Del Bono and Ermisch, 2009, Hoff-Ginsberg, 1998, Salt and Redshaw, 2006, Stoelhorst et al., 2003, Tracey and Young, 2002, Westerlund and Lagerberg, 2008).

Section snippets

Participants

The Mother–Child Cohort in Crete (“Rhea Study”) examined a sample population of pregnant women within one year, starting in February 2007, living in the prefecture of Heraklion. To be eligible for inclusion in the study, women had to have a good understanding of the Greek language and be older than 17 years of age. The first contact was made before weeks 15 of gestation, at the time of the first major ultrasound examination. Participants were invited to provide blood and urine samples and to

Reliability

Overall, the inter-rater reliability for all measures was excellent. Specifically, the inter-rater reliability for the Cognitive Scale was found to be ICCCOG = 0.990 (p < 0.001), for Receptive Communication ICCRC = 0.996 (p < 0.001), for Expressive Communication ICCEC = 0.994 (p < 0.001), for Fine Motor ICCFM = 0.924 (p < 0.001), and finally for Gross Motor ICCGM = 0.972 (p < 0.001).

Socio-demographic characteristics of mothers and infants

Table 1 presents the socio-demographic characteristics of both mothers who participated in the study (participants) and those who did

Discussion

The present study was carried out to provide insight into the early assessment of infants’ development by analysing the socio-demographic determinants affecting neurodevelopment in Crete, Greece. The results of our study suggest that several infant and parental characteristics were statistically significantly associated with neurodevelopment at 18 months. Specifically, high maternal education and being a girl were associated with high scores in nearly all neurodevelopmental scales. Moreover,

Conflicts of interest

The authors have no conflicts of interest to declare.

Acknowledgements

The Mother–Child Cohort in Crete (Rhea Study) was partly supported by the EU funded projects EnviroGenoMarkers project (FP7, Contract no ENV-2008-226756), the Integrated Project NewGeneris project (FP6, Contract no FOOD-CT-2005-016320) and HiWATE, (FP6, Contract no FOOD-CT-2006-036224). We are grateful to all those who participated in the study especially the mothers and their infants, and the whole Rhea team for their contribution and understanding. We also acknowledge Raquel Garcia Esteban,

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