Final answer:
Fetal lie, presentation, attitude, and position describe the fetus's orientation during childbirth, affecting the manner and duration of delivery. A vertex presentation with the fetus's head down is most common for vaginal birth. Breech presentations are less common, and often result in Caesarian sections.
Step-by-step explanation:
The terms fetal lie, presentation, attitude, and position describe the orientation of the fetus during childbirth. Fetal lie refers to the orientation of the fetus in relation to the mother's spine, either longitudinal or transverse. Presentation describes which fetal body part is closest to the birth canal and will deliver first. For example, in a vertex presentation, the fetus's head is down, which is the most common and associated with the greatest ease of vaginal birth. In contrast, a breech presentation, where the buttocks or feet are positioned to deliver first, occurs in fewer than 5 percent of births.
Attitude refers to the posture the fetus assumes within the uterus, such as the typical 'fetal position' with crossed arms and bent knees. Position deals with the relationship of a designated landmark on the fetal presenting part to the front, sides, or back of the maternal pelvis. The most favorable for vaginal birth is the occiput anterior position, where the fetus's head faces the maternal spinal cord, and the occiput exits the birth canal first.
A breech presentation often leads to delivery via Caesarian section in modern obstetric practice. During labor, the orientation of the fetus can influence the duration of the expulsion stage, which is the time from when the fetal head enters the birth canal until birth.