Consequences of Uteroplacental Insufficiency on Developmental and Intellectual Performances

After completing this article, readers should be able to: 1. Explain why the difference between small for gestational age and intrauterine growth restriction is important for determining time of delivery. 2. Describe the potential developmental consequences of placental insufficiency. 3. Delineate the hypotheses underlying the association between prenatal stress and developmental outcome. Deprivation of supplies is the common pathogenic factor for fetuses experiencing placental insufficiency, even if all do not exhibit hypotrophy at birth or accelerated maturation as a response to stress. Nearly one century ago, placental insufficiency was remarkably described by the French obstetrician Pierre Budin: “They are tiny, puny infants with great vitality. Their movements are untiring and their crying lusty, for their organs are quite capable of performing their allotted functions. These infants will live, for although their weight is inferior … their sojourn in the womb was longer.” (1) Since then, normative growth curves and precise determination of gestational age (GA) have permitted consensual categorization of newborns, the last advance being the identification of an intrauterine growth restriction (IUGR) subgroup among the small-for-gestational age (SGA) group (10th percentile). (2) However, this categorization remains unsatisfactory when dealing with the very preterm group for several reasons, including unknown GA in many cases and inadequacy of the current growth curves in the low range of GA. Why is it so important to make a distinction between SGA and IUGR infants? First, the cause is different: genetic factors explain a large proportion of cases in SGA infants and epigenetic factors are involved in IUGR fetuses. This current conception is elegantly summarized by Fowden: “Normal fetal growth depends on an adequate supply of nutrients and on a strict temporal relationship between tissue accretion and differentiation. During early development, the pattern of intrauterine growth is largely determined by the fetal genome but, as size …