1
Interdisciplinary Themes

Before addressing the evolution of knowledge in each area of child development, we thought it would be useful to point out the major themes that run through our discipline and guide the work in various fields.

1.1. The question of prediction

Behavioral genetics, like psychoanalysis, looks for causality in the child's past in different ways, but can we predict the child?

The retrospective approach can even prescribe, because by predicting too much, we end up creating "fate neuroses", with prophecies ending up realizing an unfavorable future for the child.

1.1.1. Prediction before birth

1.1.1.1. "To be born or not to be born", "Not to be born at all is best..." (chorus of Oedipus at Colonus)

Using prenatal diagnoses, doctors and parents can now predict the appearance of diseases and deficiencies (trisomy, cystic fibrosis, etc.); it is even more complex for the birth of a second child when the first child has one of these types of hereditary disease. We can see the risks of eugenics.

Even in the case of normal development, the choice of a child's sex has led to disparities in some countries. Are we going to go as far as selective pairing of parents based on their DNA?

Two strategies are currently available to parents in the case of a proven hereditary risk: to modify the embryo through biotechnology or to medically terminate the pregnancy. Both can pose moral or ethical dilemmas for the parents. This theme will be taken up again in Chapter 2, on the fetus.

1.1.1.2. Predicting adult problems from childhood

The links between behavioral problems in children and problems in adulthood are well known and affect almost all areas of life. Various mechanisms may be at work:

• - the continuity of a trait from childhood to adult life (the anxious child becomes an anxious adult);
• - childhood problems and adult problems may be linked because they share the same risk factors (such as poverty and violence).

1.2. Development concepts

Two major development models have always been in conflict: development in stages and continuum development.

In the stage model (Piaget, Freud), the development of the child's intelligence or sexuality proceeds in chronological stages, from an initial state to a final state, each stage building on the previous one.

In the continuum model (Wallon, Zazzo), the stages exist only in the mind of the observer, but the development for the subject himself proceeds progressively, from birth to death.

Does this "continuum or stages" debate still make sense? Piaget's stages, or "staircase" model, from the first sensorimotor intelligence step to the final abstract intelligence step, is challenged today, especially in the work on newborns. In this book, we will see that some acquisitions are much earlier than Piaget thought and that the development of intelligence is not linear.

Another more recent model is Siegler's "waves" model: the newborn has various cognitive strategies at his disposal from birth that compete to understand the world; he therefore launches them like overlapping waves to arrive on the shore of understanding. With experience, and depending on the situation, the child will use one strategy or another.

We can also evoke the progressive stabilization of synapses, learning by loss, by inhibition or Bachelard's "philosophy of no"; the child's neurocognitive development takes place through a multiplication and then pruning of the connections between neurons, hence a reduction in the brain's gray matter. This pruning has been described by Changeux (1983) as a selective stabilization of synapses by a "neural Darwinism" mechanism; this maturation takes place in successive waves according to the areas of the brain: first, the regions associated with basic sensory and motor functions, then, up to the end of adolescence, the regions associated with higher cognitive control (notably, inhibitory control). The child also learns to inhibit strategies through experience, imitation or instruction from others.

This leads to a nonlinear development model made up of learning curves revealing explosions, collapses and turbulence.

Functional magnetic resonance imaging (fMRI) allows the visualization of brain dynamics corresponding to the activation/inhibition of cognitive strategies at different ages (macrogenesis) or during learning at a particular age (microgenesis).

1.2.1. How can we study development? The methodology

The "royal" way to study development is therefore through longitudinal studies; the principle is always to follow the children during their development, studies can start before or after birth, or during the adolescence of the subject.

The following are some recent examples; their contributions will then be presented through the course of the book in relation to the various fields of development.

1.2.1.1. Studies with a prenatal onset: the EDEN study (study of pre- and postnatal determinants of child development and health)

This study (Heude and Forhan 2015) aimed to investigate prenatal and postnatal determinants of child health and development in a French population. Pregnant women at <24 weeks of amenorrhea were recruited to the Poitiers and Nancy university hospitals between 2003 and 2006. Exclusion criteria were: being under 18 years of age, no informed consent, functional illiteracy in French, history of diabetes, plan to change address or no social security coverage.

Of the 3,758 women invited to participate, 2,002 (53%) agreed to enroll in the study. Women with multiple pregnancies were also excluded. With deaths, the number fell to 1,899 infants enrolled at birth. Written informed consent was obtained twice from parents: at enrollment and after the child's birth.

All variables included in the analysis were collected by means of paper self-completed questionnaires, with the exception of anthropometric measurements, which were assessed by clinical examination, and birth term, which was removed from medical records. The children were then followed up at 4, 8, 12 and 24 months and at five or six years.

1.2.1.2. Studies from birth

1.2.1.2.1. The ELFE Study (French longitudinal study since childhood)

The ELFE (Étude Longitudinale Française depuis l'Enfance) Study is a nationally representative, multidisciplinary birth cohort of infants born to 18,040 women in 349 maternity hospitals in France in 2011. The protocol, design and recruitment procedures of the ELFE survey have been previously described (Vandentorren and Pirus 2006). Participating mothers and infants were recruited while in the maternity units and subsequently monitored. Exclusion criteria were: stillbirth, birth before 33 weeks gestation, multiple births and plans to leave metropolitan France within three years. Mothers had to be able to give informed consent in one of the study languages (French, English, Arabic and Turkish).

Maternity data was collected using standardized interviews by trained interviewers and self-completed questionnaires. Information on obstetric characteristics was collected from maternal recalls and medical records. Two months after delivery, data was collected via telephone interviews.

Information is collected annually and then every two years up to the age of 20, in the form of questionnaires (at home or by telephone), biological samples (at birth, three and six years), environmental measurements and follow-up logbooks (standardized collections of anthropometric measurements, etc.). The medical data is relayed by the parents from health records and completed by a medical examination at two years and a health check-up at six years.

1.2.1.2.2. The EPIPAGE 2 Study (epidemiological study on low-gestational-age infants)

The EPIPAGE (Étude épidémiologique sur les petits âges gestationnels) 2 Study is a national study to better understand the development of premature infants. The study focuses on infants divided into three groups: extremely premature (born before the end of the sixth month of pregnancy), very premature (born before the end of the seventh month of pregnancy) and moderately premature (born at the beginning of the eighth month of pregnancy). These children are followed from birth to age 12.

1.2.1.2.3. The 1958 British National Child Development Study

The 1958 British birth cohort study was based on a sample of 18,558 British subjects, all infants born within one week in March 1958 (n = 17,638) and immigrants recruited at ages 7, 11 and 16 (n = 920). Information was collected from parents, teachers and physicians during childhood (birth, 7, 11 and 16 years) and from cosigners during adulthood (23, 33, 42, 45 and 50 years).

1.2.1.2.4. The "Lifeways Cross-Generation Cohort" Study in the Republic of Ireland

Participants were 943 mothers and their offspring, 890 fathers, 938 maternal grandmothers, 700 maternal grandfathers, 537 paternal grandmothers and 553 paternal grandfathers. Infant birth weights were standardized based on gestational age (1990 UK population) and then categorized as low, high or normal birth weights.

Four birth periods were considered: the country's...