Prenatal maternal stress has been shown to impair functioning in nonhuman primate offspring. Little is known about the effects of prenatal stress on intellectual and language development in humans because it is difficult to identify sufficiently large samples of pregnant women who have been exposed to an independent stressor. We took advantage of a natural disaster (January 1998 ice storm in Québec, Canada) to determine the effect of the objective severity of pregnant women's stress exposure on general intellectual and language development of their children. Bayley Mental Development Index (MDI) scores and parentreported language abilities of 58 toddlers of mothers who were exposed to varying levels of prenatal stress were obtained at 2 y of age. The hierarchical multiple regression analyses indicated that the toddlers' birth weight and age at testing accounted for 12.0% and 14.8% of the variance in the Bayley MDI scores and in productive language abilities, respectively. More importantly, the level of prenatal stress exposure accounted for an additional 11.4% and 12.1% of the variance in the toddlers' Bayley MDI and productive language abilities and uniquely accounted for 17.3% of the variance of their receptive language abilities. The more severe the level of prenatal stress exposure, the poorer the toddlers' abilities. The level of prenatal stress exposure accounted for a significant proportion of the variance in the three dependent variables above and beyond that already accounted for by non-ice storm-related factors. We suspect that high levels of prenatal stress exposure, particularly early in the pregnancy, may negatively affect the brain development of the fetus, reflected in the lower general intellectual and language abilities in the toddlers. The effects of prenatal maternal stress (PNMS) on offspring abilities have been examined extensively in nonhuman primates in well-controlled studies. In general, increases in PNMS are related to elevated levels of inhibited behavior and decreases in cognitive and neuromotor functioning (1, 2). For example, both chronic stress during pregnancy (1) and 2 wk of ACTH administration at midgestation (2) predict poorer attention during infancy. Moreover, mild prenatal maternal stress is associated with delayed object permanence (3). In human populations, maternal anxiety (4) and moderate to severe life events (5, 6) during pregnancy increase the risk of obstetric complications such as preeclampsia, fetal distress, preterm birth, and low birth weight and predict an increase in neonatal crying (7), acute health problems during the first year (8), and behavioral and/or emotional problems at 4 y of age (9). Moreover, Apgar scores at 5 min were 2 SD lower in newborns of anxious mothers (4), indicating birth trauma. In terms of cognitive functioning in humans, PNMS has been linked to poorer performance. For example, a study of the long-term effects of PNMS associated with a major earthquake demonstrated that 18-y-olds who were exposed prenatally had signif- Received February ...

Brief daily exercise of the walking and placing reflexes in the newborn leads to a high rate of responding by 8 weeks and to an earlier onset of walking alone. There appears to be a critical period during which the walking response can be transformed intac from a reflexive to an instrumental action.

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Toddler toy play evolves in a predictable manner and provides a valid, nonverbal measure of cognitive function unbiased by social behaviors. Research on prenatal maternal stress (PNMS) indicates that exposure to stress in utero results in developmental deficits. We hypothesized that children exposed to high objective PNMS from a natural disaster early in pregnancy would exhibit higher rates of stereotypical play and lower rates of mature functional play than their low-stress counterparts would. We examined the functional play abilities of 52 2-year-olds exposed to low or high objective PNMS from a natural disaster within a nonstructured play session. Toddlers exposed to high objective PNMS, subjective PNMS, or both exhibited less functional and more stereotypical toy play, with less diversity, compared to toddlers exposed to low PNMS. PNMS appears to affect functional play development in toddlers negatively. These results replicate delays in language and intellectual functioning observed in these toddlers using the Bayley Scales.The purpose of this study was to investigate whether in utero exposure to varying levels of prenatal maternal stress (PNMS) influences the development of play abilities in young children. Although research with animals suggests that PNMS has a negative effect on cognitive development (Schneider, 1992), research with humans is hampered by ethical constraints. Relying on a natural disaster to provide the ranSend correspondence to Suzanne King,

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