Study design and sample
A descriptive and correlational design has been used in this study. The
population of the study comprised all the pregnant women applying to the
obstetrics polyclinic of a university hospital. No study was observed
which investigated the effects of independent variables on the prenatal
breastfeeding self-efficacy of pregnant women, which is regarded to be
the primary result of this study, and as such, no results were obtained
which could be used in the sample calculation. Having predicted the
effect of independent variables on pregnant women’s prenatal
breastfeeding self-efficacy scale scores to be f2: .08 (small effect)
based on the multiple regression analysis results, it was determined
that at least 285 pregnant women should participate in the study as per
the sample number calculation done on the G*Power (3.1.9.2) software
with 5% alpha margin of error (two-sided) and 90% power. Taking into
account the possibility of losses to occur during the data collection
process, it was decided that 314 pregnant women would participate in the
study, 10% more than the number found in the sample number calculation.
Based on the value of R2: .25 obtained from the regression analysis
which determined seven independent variables to have an effect on
pregnant women’s prenatal breastfeeding self-efficacy scores, regarded
to be the primary result of this study, the effect size and the power
were found to be f2: .33 (medium effect) and 1.00 (100%) respectively
in the post hoc power analysis done on the G*Power (3.1.9.2) software,
and the sample number of the study was determined to be sufficient. The
study was conducted in a random sampling design, one of the
non-probability sampling methods, choosing among pregnant women applying
to the obstetrics polyclinic of a university hospital. Pregnant women
who were in their third trimester (27th pregnancy week
and above), had a single and healthy fetus, had a spontaneous pregnancy
and had no health problems were included in the study.