Which of the following is an example of a primitive reflex that is present in newborns and typically disappears by 3-4 months of age?

A) Decrease the heart rate of the fetus:
Lying on the left side can sometimes help improve fetal oxygenation, especially if there is a concern about reduced blood flow from compression of the inferior vena cava, which can occur when the mother lies on her back. However, the primary rationale for this position is to prevent supine hypotension, not specifically to decrease fetal heart rate. In fact, side-lying can promote better oxygen exchange, which can indirectly benefit the fetal heart rate.

B) Aid the women while she pushes:
While a left-side lying position may offer comfort during labor and can help with uterine positioning, it is not specifically intended to aid in the pushing phase. Positions such as squatting or hands-and-knees are generally more helpful during the pushing phase because they can facilitate effective pushing and help the baby descend into the birth canal. The left-side position is more about circulation and preventing hypotension.

C) Prevent supine hypertension:
Supine hypotension occurs when the pregnant woman lies flat on her back, which can compress the inferior vena cava and reduce blood return to the heart. This leads to a drop in blood pressure and can compromise both maternal and fetal circulation. The left-side position is recommended because it helps to prevent this compression and allows optimal blood flow to both the mother and fetus, improving oxygenation and circulation.

D) Prevent the client from falling out of bed:
While lying on the left side may make the woman feel more stable, the primary reason for this position is to prevent supine hypotension, not to prevent her from falling out of bed. The nurse would ensure safety by using appropriate bed rails and monitoring, but the primary concern is supporting optimal circulation, not preventing falls.

A) Uterine contractions:
While uterine contractions cause significant pain and discomfort during labor, particularly in the first and early second stages, by the time the client reaches the second stage of labor, the cervix is fully dilated, and the main cause of pain and pressure is no longer from the contractions themselves. Instead, the pain and pressure described in the second stage are primarily due to the fetal head descending through the birth canal, applying pressure to the perineum.

B) The fetal head applying pressure:
The pain and pressure reported in the second stage of labor are primarily due to the fetal head descending into and through the birth canal, putting pressure on the cervix, vagina, perineum, and pelvic floor. This pressure is a major source of discomfort in the second stage, as the fetal head stretches the tissues of the perineum, which is essential for facilitating birth. The sensation of pressure on the pelvic floor is often described by clients during this stage.

C) Nerve stimulation:
Nerve stimulation occurs during labor as a result of uterine contractions and the fetal descent, which can cause radiating pain to the lower back, thighs, and pelvic region. However, the specific pain and pressure in the pelvis and perineum described by the client are more directly related to the fetal head applying pressure, rather than generalized nerve stimulation. Nerve stimulation may contribute to pain but is not the primary cause of the pelvic and perineal pressure at this stage.

D) Cervical dilation:
Cervical dilation occurs in the earlier stages of labor (latent and active phases), and while it contributes to pain during these stages, by the second stage, the cervix should be fully dilated (10 cm). The pain and pressure that the client is feeling in the second stage are less about cervical dilation and more about the descent of the fetal head through the birth canal and its pressure on the perineum and pelvic floor.