Prenatal stress and mixed-handedness.

Atypical lateralization, as indicated by mixed-handedness, has been related to diverse psychopathologies. Maternal prenatal stress has recently been associated with mixed-handedness in the offspring. In the present study, this relationship was investigated further in a prospective, methodologically comprehensive manner. Stress levels were determined three times during pregnancy by means of questionnaires and measurements of cortisol levels. The handedness of 110 6-y-old children (48 boys) was determined by independent observers. Mixed handedness was defined as using the opposite hand for one or more of the tested activities. Logistic regression analysis showed that more maternal daily hassles in late pregnancy and maternal mixed-handedness increased the chance of mixed-handedness in the offspring. In contrast, more pregnancy-related fear in late pregnancy and a longer duration of gestation were associated with a smaller chance of being mixed-handed. Prenatal stress measured during the first two periods of pregnancy or determined by cortisol was not related to mixed-handedness in the offspring. In conclusion, reported and physiologic measures of prenatal stress in a moderately stressed pregnant population were only partly related to offspring mixed-handedness.