Ultrasound during pregnancy and subsequent childhood non-right handedness: a meta-analysis.

Objective A possible association between ultrasound during pregnancy and subsequent non-right handedness among children has been suggested. The association has been reported to be stronger among boys. The aim of the present study was to explore this further through a meta-analysis of two follow-up studies of three randomized controlled trials of routine ultrasonography during pregnancy. Design Handedness was assessed through a questionnaire to the parents, and 4715 children at the age of 8–9 years were included in the meta-analysis. Results There was no statistically significant difference in the prevalence of non-right handedness between the ultra-sound-screened children and the controls, but there was a statistically significant difference in a subgroup analysis among the boys. Exploratory analyses according to exposure or non-exposure indicated an even stronger association between ultrasound and non-right handedness. Conclusions A conservative analytical approach indicates no association between ultrasound in utero and subsequent non-right handedness. The results from the exploratory analyses must be interpreted with caution. There is still a need for further research. [ABSTRACT FROM AUTHOR]