A 37 weeks' gestation patient with a scheduled nonstress test (NST) has the following vital signs recorded over two days: 2/10 1535: BP 162/100, HR 78, SpO2 100%; 2/10 1600: BP 168/100, HR 76, SpO2 100%; 2/11 1200: BP 166/100, HR 84, SpO2 99%; 2/11 1818: BP 152/86, HR 78, SpO2 99%. The nurse anticipates needing to administer Magnesium Sulfate to prevent which of the following complications?