What is the reasoning for withholding oxytocin with a systolic blood pressure of >160?

Thank you for your question. Although the numbers are small, studies have shown that the hemodynamic effects of oxytocin on patients with severe preeclampsia are not predictable. Oxytocin may cause decreased cardiac output and subsequent hypotension. For this reason, oxytocin is contraindicated in patients with a systolic BP > 160 mm Hg. I have attached a link to a  2011 study on this.   https://doi.org/10.1016/j.ijoa.2010.10.004