Background: There is accumulating evidence for a link between maternal stress during pregnancy and later behavioural and emotional problems in children. Little research has examined other developmental outcomes.
Aim: To determine the effect of maternal stress during pregnancy on offspring language ability in middle childhood.
Study design: Longitudinal pregnancy cohort-study.
Subjects: A total of 2900 mothers were recruited prior to the 18th week of pregnancy, delivering 2868 live births. The language ability of just under half of the offspring cohort (n=1309; 45.6% of original sample) was assessed in middle childhood (Mean age=10;7, Standard deviation=0;2, range: 9;5-11;11).
Outcome measures: Language ability was measured using the Peabody Picture Vocabulary Test-Revised (PPVT-R). The main predictor variable was the frequency of 10 typically 'stressful' life events experienced by mothers during early and/or late pregnancy. Children were allocated to four groups according to whether they were exposed to high maternal stress (>or=2 life events) during early pregnancy only, late pregnancy only, both, or neither.
Results: Mixed-effects regression analyses revealed no association between the maternal experience of two or more stressful life events at any time-point during pregnancy and PPVT-R scores. Repeating the regression analyses with more lenient (>or=1 life events) or strict (>or=3 life events) thresholds for defining high-levels of maternal stress did not alter the pattern of findings.
Conclusions: Maternal experience of typically stressful life events during pregnancy has a negligible effect on vocabulary development to middle childhood.
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