The maternity nurse understands that as the uterus contracts during labor, maternal-fetal exchange of oxygen and waste products:

Choice A rationale
Fetal sleep cycles cause temporary decreased variability in FHR, typically lasting 20 minutes or less. FHR baseline remains normal. Normal FHR variability is 6-25 bpm.
Choice B rationale
Head compression during contractions leads to early decelerations in FHR, not decreased variability. Early decelerations are a normal response to pressure on the fetal head.
Choice C rationale
Fetal hypoxemia causes decreased variability but usually persists for longer than 20 minutes. It indicates compromised oxygen supply, requiring immediate intervention.
Choice D rationale
Umbilical cord compression leads to variable decelerations in FHR rather than decreased variability. These decelerations vary in onset, duration, and intensity.

Choice A rationale
The occiput anterior position is optimal for labor and birth due to the fetal head's alignment with the maternal pelvis, reducing resistance and facilitating descent through the birth canal.
Choice B rationale
The occiput posterior position can lead to prolonged labor and increased discomfort because the fetal head does not align with the maternal pelvis as effectively as in the anterior position.
Choice C rationale
The mentum posterior position is uncommon and often requires medical intervention, as the chin-first presentation can obstruct labor progression and prevent the fetus from passing through the birth canal.
Choice D rationale
The occiput transverse position may result in a difficult labor due to the fetal head being oriented sideways, hindering descent and potentially necessitating medical assistance or operative delivery.