A nurse is teaching an assistive personnel to measure a newborn's respiratory rate. Which of the following statements indicates an understanding of why the respiratory rate should be counted for a complete minute?

Choice A: This is incorrect because weight less than the 10th percentile (SGA) means that the infant is smaller than expected for the gestational age, but not necessarily low birth weight. SGA infants may have intrauterine growth restriction due to maternal, placental, or fetal factors, but they may also be constitutionally small. SGA infants are at risk for hypoglycemia, hypothermia, polycythemia, and perinatal asphyxia.

Choice B: This is incorrect because weight greater than the 90th percentile means that the infant is larger than expected for the gestational age, but not necessarily high birth weight. Infants with weight greater than the 90th percentile are called large for gestational age (LGA) or macrosomic. LGA infants may have maternal diabetes, genetic factors, or post-term pregnancy as causes, but they may also be constitutionally large. LGA infants are at risk for birth trauma, shoulder dystocia, hypoglycemia, and respiratory distress.

Choice C: This is incorrect because weight between the 10th and 90th percentile means that the infant is appropriate for the gestational age (AGA), but not necessarily normal birth weight. AGA infants have a weight that matches their gestational age and are considered healthy and well-nourished. However, some AGA infants may have low or high birth weight depending on their gestational age at birth.

Choice D: This is the correct answer because low birth weight (LBW) is defined as a weight of 2500g or less at birth, regardless of the gestational age. LBW infants may be preterm (born before 37 weeks of gestation), term (born between 37 and 42 weeks of gestation), or post-term (born after 42 weeks of gestation). LBW infants are at risk for infection, bleeding, jaundice, and neurodevelopmental problems.

Choice A) Newborns are abdominal breathers is incorrect because this is not a reason why the respiratory rate should be counted for a complete minute, but rather a characteristic of how newborns breathe. Abdominal breathing means that the diaphragm and the abdominal muscles are the main muscles used for breathing, rather than the chest muscles. Newborns are abdominal breathers because their chest wall is more compliant and less stable than adults, and their intercostal muscles are not fully developed. Abdominal breathing does not affect the accuracy or duration of measuring the respiratory rate, as long as the abdomen is visible and palpable. Therefore, this response is irrelevant and inaccurate.

Choice B) Activity will increase the respiratory rate is incorrect because this is not a reason why the respiratory rate should be counted for a complete minute, but rather a factor that can influence the respiratory rate. Activity means any physical or mental exertion that requires more oxygen and energy from the body. Activity can increase the respiratory rate, as well as the heart rate and blood pressure, to meet the increased oxygen demand and carbon dioxide removal. However, activity does not affect the accuracy or duration of measuring the respiratory rate, as long as the newborn is calm and resting during the measurement. Therefore, this response is irrelevant and inaccurate.

Choice C) The rate and rhythm of breath are irregular in newborns is correct because this is a reason why the respiratory rate should be counted for a complete minute. The rate and rhythm of breath refer to how fast and how regularly one breathes. Newborns have an irregular rate and rhythm of breath, which means that they breathe at different speeds and intervals, sometimes pausing for a few seconds between breaths. This is normal and harmless for newborns, as long as they do not stop breathing for more than 20 seconds or show signs of distress. However, it can make it difficult to measure the respiratory rate accurately, as counting for a shorter period may not reflect the true average rate. Therefore, counting for a complete minute can ensure a more reliable measurement. Therefore, this response is clear and accurate.

Choice D) Newborns do not expand their lungs fully with each respiration is incorrect because this is not a reason why the respiratory rate should be counted for a complete minute, but rather a feature of how newborns breathe.

Lung expansion means how much air one inhales and exhales with each breath. Newborns do not expand their lungs fully with each respiration, because they have smaller lung volumes and capacities than adults, and they breathe more shallowly and rapidly. However, lung expansion does not affect the accuracy or duration of measuring the respiratory rate, as long as the chest or abdomen movement is visible and palpable. Therefore, this response is irrelevant and inaccurate.