What is the most dangerous effect on the fetus of a mother who smokes cigarettes while pregnant?

Choice A reason: Nonreactive is not the correct result, as it indicates that the FHR does not show adequate accelerations with fetal movement. A nonreactive NST means that the FHR does not increase by at least 15 beats/min for at least 15 seconds in a 20-minute period. A nonreactive NST may suggest fetal hypoxia (low oxygen) or fetal sleep.

Choice B reason: Reactive is the correct result, as it indicates that the FHR shows adequate accelerations with fetal movement. A reactive NST means that the FHR increases by at least 15 beats/min for at least 15 seconds twice or more in a 20-minute period. A reactive NST is reassuring and suggests that the fetus is well-oxygenated and healthy.

Choice C reason: Positive is not the correct result, as it is not used to describe the NST. Positive is a term used for the contraction stress test (CST), which is a different test that measures the FHR in response to uterine contractions. A positive CST means that the FHR shows late decelerations (decreases in the FHR that begin after the peak of a contraction and return to the baseline after the contraction ends) with at least 50% of the contractions. A positive CST indicates uteroplacental insufficiency (a condition where the placenta does not deliver enough oxygen and nutrients to the fetus) and fetal distress.

Choice D reason: Negative is not the correct result, as it is also not used to describe the NST. Negative is another term used for the CST, which is a different test that measures the FHR in response to uterine contractions. A negative CST means that the FHR does not show any late decelerations during at least three contractions in a 10-minute period. A negative CST is reassuring and suggests that the fetus is well-oxygenated and can tolerate labor.

Choice A reason: This is not the correct answer, as the pregnant woman does not use glucose at a more rapid rate than the nonpregnant woman. In fact, the pregnant woman has lower fasting glucose levels and higher postprandial glucose levels than the nonpregnant woman. This is because the pregnant woman adapts to the increased fetal demand for glucose by increasing her insulin secretion and decreasing her hepatic glucose production.

Choice B reason: This is the correct answer, as placental hormones are antagonistic to insulin, thus resulting in insulin resistance. Insulin resistance is a condition where the cells do not respond well to insulin and require more insulin to maintain normal glucose levels. Placental hormones, such as human placental lactogen, progesterone, and cortisol, increase the insulin resistance of the maternal tissues, especially in the second and third trimesters of pregnancy. This is to ensure that the fetus has enough glucose supply, as the placenta is not insulin resistant and can transport glucose to the fetus².

Choice C reason: This is not the correct answer, as pancreatic function in the islets of Langerhans is not affected by pregnancy. The islets of Langerhans are clusters of cells in the pancreas that produce hormones, such as insulin and glucagon, that regulate glucose metabolism. Pregnancy does not impair the function of the islets of Langerhans, but rather stimulates them to increase their size and number. This is to compensate for the increased insulin resistance and glucose demand of the pregnancy.

Choice D reason: This is not the correct answer, as the pregnant woman does not increase her dietary intake significantly. The pregnant woman needs to consume adequate calories and nutrients to support the fetal growth and development, but not excessively. The recommended weight gain during pregnancy depends on the pre-pregnancy BMI of the woman, but generally ranges from 11 to 16 kg. The recommended calorie intake during pregnancy is about 300 kcal more than the pre-pregnancy intake, which is equivalent to one extra snack per day.