Where should the fetoscope be positioned to auscultate the fetal heartbeat during the third trimester?

Positioning the fetoscope against the fetus's back is correct because this is the optimal location for detecting the fetal heartbeat in the third trimester. The back of the fetus is typically where the heart is located, making it easier to collect clear sounds. As the fetus grows and approaches term, the amount of amniotic fluid decreases, and the baby's position becomes more stable, often lying in a way that allows the back to be positioned against the mother's abdominal wall.

In contrast, positioning the fetoscope above the symphysis pubis or directly above the mother's belly button is typically inadequate for accurate fetal heart sound assessment during the third trimester. These locations are generally more likely to capture maternal sounds or be too far from the heart, making it difficult to detect the heartbeat clearly.

Positioning below the umbilicus could be effective, but it does not specify that the fetoscope is aligned with the back of the fetus. Hence, while sounds may be detectable there, positioning it directly against the fetal back yields the most reliable and clear fetal heart sounds.