A 29-year-old woman, gravida 2, para 1, at 32 weeks' gestation, presents to labor and delivery reporting flank pain, fever, chills, and cramping. She is having contractions every 3-4 minutes, and the fetal heart rate baseline is 180. You check her cervix and discover a dilation of 3 cm and 100% effacement, and you see that the fetal head is floating. From the physical exam and from results of the urinalysis, you conclude that she has pyelonephritis and admit her to the hospital for intravenous antibiotics, magnesium sulfate to try to slow contractions, and steroids. Several hours later, she is having trouble breathing. Her vitals are: T 102.1F, BP 110/78, P 105, R 28, and oxygen saturation is 96% on room air. Physical exam reveals she is tachycardic but without murmurs. You hear bilateral rales over the lung bases. Her abdomen is soft, gravid, and nontender. She still has costovertebral angle tenderness. There is 2+ pedal edema. Which of the following is the most likely diagnosis?
(Pulmonary edema is a known complication of magnesium sulfate.)