Editing Shyness (section)

=== Prenatal development ===

The prevalence of shyness in some children can be linked to day length during [[pregnancy]], particularly during the midpoint of prenatal development.<ref name=daylength>Gortmaker, SL. et al. ''Daylength during pregnancy and shyness in children: results from northern and southern hemispheres''. 1997.</ref> An analysis of longitudinal data from children living at specific latitudes in the [[United States]] and [[New Zealand]] revealed a significant relationship between hours of day length during the midpoint of pregnancy and the prevalence of shyness in children. "The odds of being classified as shy were 1.52 times greater for children exposed to shorter compared to longer daylengths during gestation."<ref name=daylength /> In their analysis, scientists assigned conception dates to the children relative to their known birth dates, which allowed them to obtain random samples from children who had a mid-gestation point during the longest hours of the year and the shortest hours of the year (June and December, depending on whether the cohorts were in the United States or New Zealand).

The longitudinal survey data included measurements of shyness on a five-point scale based on interviews with the families being surveyed, and children in the top 25th percentile of shyness scores were identified. The data revealed a significant co-variance between the children who presented as being consistently shy over a two-year period, and shorter day length during their mid-prenatal development period. "Taken together, these estimates indicate that about one out of five cases of extreme shyness in children can be associated with gestation during months of limited daylength."<ref name=daylength />