Main results
The present study shows, firstly, that anxiety symptoms during pregnancy are associated with lower birth weight percentiles. Secondly, trait anxiety (STAIt) shows a higher association with lower birth weight percentiles than state anxiety (STAIs). Thirdly, regarding the effect of anxiety timing on fetal growth, although there was a certain trend, it is not clear whether the appearance of anxiety symptoms at an earlier gestational age is associated with lower birth weight percentiles. In addition, there was a negative correlation between state anxiety and gestational age at the time when anxiety symptoms first appear, suggesting that women experienced higher state anxiety when exposed to the stressful event at a lower gestational age.