During labor, a fetus with an average heart rate of 135 beats per minute over a 10-minute period would be considered to have a normal baseline heart rate.

Choice A rationale

Preeclampsia is a hypertensive disorder of pregnancy that can lead to uteroplacental insufficiency. This condition would most likely cause late decelerations in the fetal heart tracing, as it results in decreased blood flow to the placenta and an inability to compensate during contractions. The tracing is not available, but the choice is being rationalized based on the most likely cause.

Choice B rationale

Placental abruption is the premature separation of the placenta from the uterine wall. This can lead to a variety of fetal heart tracing abnormalities, including severe variable decelerations, late decelerations, or a sinusoidal pattern, often accompanied by uterine hyperactivity. The resulting fetal distress is due to decreased placental surface area for gas exchange.

Choice C rationale

Breech positioning refers to a fetus presenting buttocks or feet first. While it can complicate labor and delivery, it is not a direct cause of a specific fetal heart rate pattern. Fetal heart rate changes in a breech presentation are typically related to cord prolapse or compression during labor, not the position itself.

Choice D rationale

Hypotension in the mother can lead to decreased placental perfusion, as seen with epidural anesthesia. This can cause late decelerations in the fetal heart rate tracing due to uteroplacental insufficiency. It is a common cause of fetal distress but is more directly related to maternal blood pressure than to a specific fetal heart rate pattern.

Choice E rationale

Cord compression is a mechanical issue that obstructs blood flow through the umbilical cord. It is the most common cause of variable decelerations, which are abrupt, visually apparent decreases in the fetal heart rate. The tracing, though not available, would likely show these variable decelerations in this context.

Choice A rationale

A fetus in a longitudinal lie, cephalic presentation, is positioned with its long axis parallel to the mother's spine, with the head presenting first. This is the most common and favorable position for vaginal delivery. The illustration depicts a vertical alignment of the fetus within the uterus.

Choice B rationale

A transverse lie is a fetal malpresentation where the long axis of the fetus is perpendicular to the long axis of the mother. The fetus's head and buttocks are positioned to the sides of the mother's abdomen, with the shoulder or trunk presenting first.

Choice C rationale

A fetus in a longitudinal lie, breech presentation, is positioned with its long axis parallel to the mother's spine. The fetal buttocks or feet are presenting first into the pelvic inlet. The illustration depicts a vertical alignment of the fetus with the head at the top of the uterus.

Choice D rationale

An oblique lie is an unstable fetal position where the fetal long axis is at an angle to the maternal long axis. This position often converts to a longitudinal or transverse lie during labor. The illustration depicts an angled fetal position, but it is not a true transverse lie. .