To prevent possible retinopathy in a preterm infant requiring oxygen therapy, the nurse will:

Sternal or chest retractions. This is because sternal or chest retractions are a sign of respiratory distress in newborns, which means they are having difficulty breathing. Chest retractions occur when the baby's chest pulls in with each breath, indicating that they are using extra muscles to breathe. This can be caused by various conditions that affect the lungs, such as respiratory distress syndrome (RDS), transient tachypnea of the newborn (TTN), meconium aspiration syndrome (MAS), pneumonia, or congenital heart defects.

Choice A is not correct because mucus draining from the nose is not a symptom of respiratory distress in newborns. It is normal for newborns to have some mucus in their nose and mouth after birth, which can be cleared by suctioning or wiping.

Mucus drainage does not interfere with breathing unless it is excessive or thick.

Choice B is not correct because cyanosis of the hands and feet is not a symptom of respiratory distress in newborns. It is normal for newborns to have bluish discoloration of their hands and feet, called acrocyanosis, for the first few days after birth. This is due to immature circulation and does not indicate a lack of oxygen. Cyanosis of the central parts of the body, such as the face, lips, and tongue, is more concerning and should be reported.

Choice C is not correct because irregular heart rate is not a symptom of respiratory distress in newborns. It is normal for newborns to have some variations in their heart rate, especially during sleep cycles. The normal heart rate range for newborns is 100 to 160 beats per minute. A heart rate that is too fast (tachycardia) or too slow (bradycardia) may indicate a problem with the heart or other organs³.

This is because lochia rubra is the first stage of lochia, the vaginal discharge after giving birth. It comprises blood, shreds of fetal membranes, decidua, vernix caseosa, lanugo, and membranes. It is red in color because of the large amount of blood it contains. It lasts 1 to 4 days after birth.

Choice A is not correct because lochia alba is the last stage of lochia. It is whitish or yellowish-white in color and contains fewer red blood cells and more leukocytes, epithelial cells, cholesterol, fat, mucus, and microorganisms. It lasts from the second through the third to sixth weeks after delivery.

Choice B is not correct because there is no such thing as lochia normal. Lochia has three stages: lochia rubra, lochia serosa and lochia alba.

Choice C is not correct because lochia serosa is the second stage of lochia. It is brownish or pink in color and contains serous exudate, erythrocytes, leukocytes, cervical mucus, and microorganisms. It lasts for 4 to 12 days after delivery.