To detect human immunodeficiency virus (HIV), most laboratory tests focus on the:

Choice A reason: Taking the medication between meals will help you avoid becoming constipated is incorrect because it is not the reason why the provider instructed that she take the ferrous sulfate between meals. It is a possible benefit of taking the medication between meals, but it is not the main purpose. Iron supplements can cause constipation, but this can be prevented by drinking plenty of fluids, eating high-fiber foods, and exercising regularly.

Choice B reason: The medication can cause nausea if taken with food is incorrect because it is not the reason why the provider instructed that she take the ferrous sulfate between meals. It is a possible side effect of taking the medication with or without food, but it is not the main reason. Iron supplements can cause nausea, but this can be reduced by taking the medication with a small amount of food, such as crackers, or by taking an antiemetic medication.

Choice C reason: Taking the medication between meals will help you absorb the medication more efficiently is correct because it is the reason why the provider instructed that she take the ferrous sulfate between meals. It is the main purpose of taking the medication between meals, as iron absorption is enhanced when the stomach is empty and the pH is low. Iron supplements can interact with food components, such as calcium, phytates, and tannins, and reduce the amount of iron that is absorbed by the body.

Choice D reason: Taking the medication with food increases the risk of esophagitis is incorrect because it is not the reason why the provider instructed that she take the ferrous sulfate between meals. It is a possible complication of taking the medication without enough water, but it is not the main reason. Iron supplements can cause esophagitis, which is inflammation of the esophagus, if they are not swallowed properly or if they get stuck in the throat. This can be prevented by taking the medication with a full glass of water, sitting upright, and not lying down for at least 30 minutes after taking the medication.

Choice A reason: Infection is not a common cause of IUGR, as most infections do not cross the placenta and affect the fetal growth. However, some infections such as cytomegalovirus, rubella, or toxoplasmosis can cause congenital anomalies and IUGR.

Choice B reason: Previous preterm birth is not a direct cause of IUGR, as it does not affect the current pregnancy. However, it may indicate an underlying maternal or fetal condition that could increase the risk of IUGR, such as cervical incompetence, placental abruption, or preeclampsia.

Choice C reason: Utero-placental insufficiency is the most common cause of IUGR, as it reduces the blood flow and oxygen delivery to the fetus. It can result from maternal factors such as hypertension, diabetes, smoking, or drug abuse, or from placental factors such as placenta previa, placental infarction, or cord compression.

Choice D reason: Chronic hypertension is a risk factor for IUGR, as it can lead to utero-placental insufficiency and fetal hypoxia. However, it is not the only cause of IUGR, as other factors can also affect the placental function and fetal growth.