Compared with contraction stress test (CST), nonstress test (NST) for antepartum fetal assessment:

Choice A reason: The NST has no known contraindications, as it is a non-invasive and safe test that does not stimulate uterine contractions or cause fetal distress. It is the most widely used method of antepartum fetal surveillance.

Choice B reason: The NST is not slightly more expensive than the CST, as it requires less time and equipment. The NST usually takes 20 to 40 minutes, while the CST may take up to 2 hours. The NST only needs a fetal monitor, while the CST also needs an intravenous line and oxytocin infusion.

Choice C reason: The NST does not have fewer false-positive results than the CST, as it has a higher rate of nonreactive results that may indicate fetal compromise when there is none. A nonreactive NST is one that does not show at least two accelerations of the fetal heart rate of 15 beats per minute or more lasting 15 seconds or more in a 20-minute period.

Choice D reason: The NST is not more sensitive in detecting fetal compromise than the CST, as it has a lower predictive value for fetal well-being. A reactive NST is one that shows at least two accelerations of the fetal heart rate of 15 beats per minute or more lasting 15 seconds or more in a 20-minute period. However, a reactive NST does not rule out the possibility of fetal hypoxia or acidosis.

The correct answer is A. You may find that you need to modify your exercise to walking later in your pregnancy, around the seventh month.

Choice A reason: This is the best advice for the woman, as it acknowledges that jogging is safe and beneficial in early pregnancy, but also informs her that she may need to adjust her exercise intensity and duration as her pregnancy progresses. Walking is a low-impact aerobic activity that can be done throughout pregnancy, as long as there are no complications or contraindications. Walking can help maintain cardiovascular fitness, prevent excessive weight gain, and reduce the risk of gestational diabetes and preeclampsia.

Choice B reason: This is not a good advice for the woman, as it implies that jogging is harmful for her joints and that she should stop it immediately. Jogging is not necessarily bad for the joints, as long as the woman wears appropriate shoes, avoids uneven surfaces, and listens to her body. Jogging can also provide many health benefits for the woman and the fetus, such as improved mood, increased energy, and reduced stress².

Choice C reason: This is a false and alarming statement that may discourage the woman from exercising at all. Exercise during pregnancy is not dangerous for the fetus, unless there are specific medical conditions or complications that prevent it. Exercise during pregnancy can actually improve the fetal growth, development, and oxygenation, as well as reduce the risk of preterm birth and low birth weight.

Choice D reason: This is an unrealistic and misleading statement that may cause the woman to overexert herself or ignore the signs of discomfort or fatigue. Exercise during pregnancy may need to be modified according to the woman's changing needs, abilities, and preferences. Some factors that may affect the type, frequency, intensity, and duration of exercise during pregnancy include the trimester, the fetal position, the maternal weight, the environmental temperature, and the presence of any symptoms or complications.