Your patient is receiving magnesium sulfate for neuroprotection and preterm labor at 1 gram/hour. The most concerning vital sign below is:

Choice A reason: Correct. Naegele’s Rule adds 1 year, subtracts 3 months, and adds 7 days to the LMP. May 4 → February 11.

Choice B reason: Incorrect. April 27 is too late; it suggests nearly 12 months of gestation, which exceeds the standard 280-day pregnancy.

Choice C reason: Incorrect. February 27 overshoots the EDD by 16 days. It doesn’t follow Naegele’s precise calculation.

Choice D reason: Incorrect. April 11 is far beyond the expected delivery window and reflects a miscalculation of gestational length.

Choice A: Polyhydramnios is not a cause of variable decelerations. Polyhydramnios is a condition where there is an excessive amount of amniotic fluid, which can cause complications such as preterm labor, placental abruption, and cord prolapsE. Polyhydramnios can cause late decelerations, which are a sign of uteroplacental insufficiency and fetal hypoxiA.

Choice B: Fetal head compression is not a cause of variable decelerations. Fetal head compression is a normal physiological response to the uterine contractions and the descent of the fetal head into the pelvis. Fetal head compression can cause early decelerations, which are a benign and reassuring pattern that mirror the contractions.

Choice C: Umbilical cord compression is a cause of variable decelerations. Umbilical cord compression is a condition where the blood flow through the umbilical cord is reduced or interrupted, which can result from cord prolapse, cord knots, or cord wrapping around the fetal neck or limbs. Umbilical cord compression can cause variable decelerations, which are abrupt and irregular decreases in the FHR that vary in shape, duration, and timinG.

Choice D: Maternal fever is not a cause of variable decelerations. Maternal fever is a condition where the mother's body temperature is elevated, which can indicate an infection or inflammation. Maternal fever can cause tachycardia, which is a high FHR above the normal range of 110 to 160 beats/min.