Strengths and limitations
The main limitation of this study is the small sample size; it is likely
that higher sample sizes may have led to the conclusion that both trait
anxiety and state anxiety are associated with lower birth weight
percentiles. Nevertheless, this study was designed around specific
stressful circumstances, during the COVID-19 pandemic lockdown, which
represented an ideal scenario for investigating the effects of anxiety
on birth weight, despite the reduced sample size. Another limitation of
this study may be the selection bias due to including different anxiety
symptoms according to the trimester of pregnancy. However, in a previous
study conducted by our group, no statistically significant differences
were found when analyzing STAIs and STAIt scores according to trimester
of pregnancy. Finally, anxiety cannot be induced in an experimental
research setting for ethical reasons. Therefore, the fact that this
study included patients that were exposed to stressful circumstances in
real life is the major strength of the present study.