Final answer:
The first time to auscultate the fetal heart is most likely during Month 4 of pregnancy.
Step-by-step explanation:
The first time you would most likely first auscultate the fetal heart is during Month 4 of pregnancy.
Based on fetal development, the heart begins beating and pumping blood around day 21 or 22 after fertilization, which is around the third week of pregnancy.
By Month 4, the heart is well-developed and the fetal heart sound can typically be heard using a stethoscope or a Doppler device.