Le stress prénatal maternel et les problèmes comportementaux chez les enfants : effet modérateur de la consistance de la discipline

Prenatal maternal stress (PNMS) is a widely studied concept, both by objective and subjective methods. Some researchers assess women's symptoms of anxiety and depression during pregnancy, while others prefer to measure cortisol levels in pregnant women. For this thesis, PNMS was measured by two different methods: either exposure of pregnant women to a natural disaster, or exposure of these same pregnant women to more common stressful life events. Since it is well established that this type of stress has a negative impact on the pregnant woman as well as on the development of the unborn child, it is now of interest to increase research on ways to mitigate the consequences of such stress. In animal studies, we know that rearing conditions and environmental enrichment seem to reverse the effects of PNMS, but we do not know whether, in humans, good parental structure, that is, a structured framework with predictable and consistent rules, can protect children from the effects of PNMS. The aim of this thesis is, therefore, to increase understanding of the protective effect of parental structure in the development of children who have been exposed to different types of PNMS.  This goal can be achieved through an international collaboration initiated by Dr. Suzanne King following the 2008 floods in the state of Iowa. Following the disaster, Dr. King contacted Dr. O'Hara to assess the severity of flood stress in pregnant women and to determine the effects of this stress on their children. Following the recruitment of mothers, the children in the sample were assessed at the ages of 2, 4, 5 and 7 years. This thesis consists of three studies. The first study examines the moderating effect of parental structure on the associations between PNMS caused by a natural disaster and behavioural problems in the Iowa Flood Study children at age 7 years as reported by their mothers. The results indicate that consistent parenting protects boys who have been exposed to PNMS from various symptoms of internalizing and externalizing problems. The second study also examines the issue of the protective effect of parental structure on associations between PNMS and behavioural problems, as reported by their mothers, in the Iowa Flood Study seven-year-olds. However, this study looked at the influence of PNMS when it is caused by life events that are more common than a natural disaster while controlling for the severity of their flood exposure. Again, the results of this study reveal that consistent parenting plays the role of a protective factor in boys who have been exposed to PNMS caused by stressful life events, but only with regard to externalizing behaviour. The third study reconsiders the protective effect of parental structure on the links between PNMS and behavioral problems of children who have been exposed to a natural disaster. However, for this study, children's behaviors were not assessed by a questionnaire, but rather by an observational method (task of frustration). However, the limitations of this study did not allow us to observe the effects of parental structure. In summary, our results show that the implementation of a structured and consistent framework can overcome, and even reverse, the consequences of PNMS on boys' behaviour.

Keyphrases: Prenatal stress, Natural disaster, Stressful life events, Parental supervision, Resilience, Child development, Behavioral problems