In which situation is magnesium sulfate particularly indicated?

Magnesium sulfate is particularly indicated in severe preeclampsia with neurological symptoms due to its neuroprotective properties. In cases of severe preeclampsia, there is a risk of seizures, which can lead to significant maternal and fetal morbidity. Magnesium sulfate is used in this context primarily to prevent the occurrence of seizures, a condition known as eclampsia. The use of magnesium sulfate can stabilize the patient's condition by reducing the likelihood of seizures and helping to manage high blood pressure levels associated with this serious pregnancy complication.

The other situations, while concerning, do not share the same urgency or specific indication for the use of magnesium sulfate. For example, new-onset hypertension with visual disturbances could indicate the potential for preeclampsia, but without the presence of severe symptoms or seizures, magnesium sulfate is not necessarily the first line of treatment. Preterm labor without signs of distress may warrant the use of other medications to manage contractions or to promote fetal lung maturity but does not directly relate to magnesium sulfate’s primary use in severe preeclampsia. Chronic hypertension managed with medication needs careful monitoring and treatment but does not specifically require magnesium sulfate unless there are other complicating factors like severe preeclampsia present.