A nurse is reinforcing teaching about the correct use of infant car seats with the parent of a newborn.
Which of the following statements by the parent indicate an understanding of the teaching?

Choice A rationale

Calcium is essential for fetal bone and tooth development, as well as for maternal skeletal integrity, muscle function, and blood clotting. Although crucial, an increase in calcium intake (normal recommended intake is 1000 mg/day for most pregnant women) is primarily aimed at skeletal and cellular health, not specifically at the physiological increase in maternal blood volume, which necessitates increased erythrocyte production and plasma volume.

Choice B rationale

Vitamin E is an important fat-soluble antioxidant that protects cell membranes from oxidative damage and plays a role in red blood cell (RBC) integrity. While it is necessary for overall maternal and fetal health, its primary function is not directly linked to the significant expansion of maternal plasma and erythrocyte mass, which is the physiological basis for the approximately 30% to 50% increase in maternal blood volume during pregnancy.

Choice C rationale

Vitamin D is a fat-soluble vitamin critical for intestinal absorption of calcium and phosphorus, thereby maintaining optimal bone mineralization and immune function. Although supplementation is often necessary, especially in those with limited sun exposure (normal range 20-50 ng/mL), its primary role is in calcium homeostasis and immune function, not as a direct substrate for the substantial increase in maternal plasma volume and red blood cell mass during gestation.

Choice D rationale

Iron is a fundamental component of the heme group in hemoglobin, which is crucial for oxygen transport by red blood cells (RBCs). The approximately 45% increase in maternal blood volume during pregnancy requires a substantial increase in RBC production (erythropoiesis) to prevent dilutional anemia. Therefore, increased iron intake (normal recommended intake 27 mg/day) is vital for the necessary synthesis of hemoglobin to support this physiologic increase in maternal erythrocyte volume.

Choice A rationale

Nalbuphine hydrochloride is a synthetic opioid agonist-antagonist analgesic often used for pain relief during labor. Its agonist effects on kappa (κ) opioid receptors in the central nervous system lead to analgesia and common side effects, including central nervous system depression. Sedation is a frequent manifestation of this effect, caused by the drug's action on brain centers controlling arousal.

Choice B rationale

Nalbuphine primarily acts as an opioid, and its μ-receptor antagonist activity counteracts some opioid effects, but typical opioid-related gastrointestinal effects include decreased peristalsis, often leading to constipation. Diarrhea is not a common or expected adverse effect of nalbuphine; instead, it tends to slow gut motility due to its opioid effects on the enteric nervous system.

Choice C rationale

Opioid use, including nalbuphine, can sometimes lead to the adverse effect of urinary retention, due to increased detrusor muscle tone and internal sphincter spasm, which is a suppression of the micturition reflex. Diuresis, which is an increased or excessive production of urine, is not a recognized adverse effect of this medication.

Choice D rationale

Opioids, such as nalbuphine, typically interact with the thermoregulatory centers in the hypothalamus, often resulting in hypothermia due to vasodilation and decreased metabolic rate, not fever. Fever (pyrexia) is not a common or characteristic adverse effect associated with the administration of nalbuphine hydrochloride during labor.