Only women who were able to complete a questionnaire
in Norwegian could be included in the study, and
63.0% of the eligible women completed the questionnaire.
We have no information on the prevalence of fear
of childbirth in the non-participating women. However,
there was no difference in the use of epidural analgesia
in our study population compared with all women in
Norway with intended vaginal delivery (28.1% versus
27.2%). The prevalence of the different modes of delivery
was also similar (The Medical Birth Registry of Norway,
www.mfr.no). Although our study sample may be skewed
with regard to the prevalence of fear of childbirth, it is
unlikely that the directions of our estimated associations
are erroneous.
of labour duration for women with late arrival to
the maternity ward is not likely to have biased our main
findings.