A nurse is caring for a client who is receiving magnesium sulfate for pre-term labor.

Which of the following assessments should the nurse perform to evaluate the therapeutic effect of the medication?

Tocolytics are a category of drugs used to delay the labor process.These may be used in situations when a pregnant person begins showing signs of preterm labor —which is any time before 37 weeks of completed pregnancy.Tocolytics may help delay labor by two to seven days.

Some possible explanations for the other choices are:

• Choice A. Administering intravenous fluids.

This is not a correct answer because intravenous fluids are not effective in suppressing uterine contractions.They may be used to correct dehydration or electrolyte imbalance, which can sometimes trigger preterm labor, but they are not a primary intervention for preterm labor.

• Choice C. Administering corticosteroids.

This is not a correct answer because corticosteroids are not tocolytics.They do not stop or slow down uterine contractions, but they help accelerate fetal lung maturity and reduce the risk of neonatal respiratory distress syndrome and other complications of prematurity.

Corticosteroids are often given along with tocolytics, but they have a different function and mechanism of action.

• Choice D. Administering antibiotics.

This is not a correct answer because antibiotics are not tocolytics.They may be used to treat infections that can cause or complicate preterm labor, such as chorioamnionitis or group B streptococcus, but they do not directly affect uterine contractions.

Antibiotics may be given along with tocolytics, but they have a different function.

This is because assessing fetal heart rate is the most important action to take first when a client has prelabor rupture of membranes (PROM) at 34 weeks of gestation and oligohydramnios.Fetal heart rate can indicate fetal well-being, distress, or infection.Oligohydramnios can increase the risk of umbilical cord compression and fetal hypoxia.

Choice A is wrong because administering IV fluids is not the first priority in this situation.IV fluids may be given to prevent dehydration, enhance uterine blood flow, or augment labor, but they are not as urgent as assessing fetal heart rate.

Choice B is wrong because obtaining a urine specimen is not the first priority in this situation.A urine specimen may be obtained to check for infection, proteinuria, or glucose levels, but they are not as urgent as assessing fetal heart rate.

Choice D is wrong because inserting an indwelling urinary catheter is not the first priority in this situation.An indwelling urinary catheter may be inserted to monitor fluid balance, prevent bladder distension, or reduce the risk of infection, but they are not as urgent as assessing fetal heart rate.

Normal ranges for fetal heart rate are 110 to 160 beats per minute.Oligohydramnios is defined as an amniotic fluid index of less than 5 cm.