All of the following are associated with placental abruption, EXCEPT:

Placental abruption occurs when a previously normally implanted placenta separates from the endometrial wall. This can occur secondarily to vascular changes or mechanical sheer forces. Both cocaine and cigarette smoking result in vascular constriction which results in acute vasospasm, elevated total peripheral resistance, and an acute increase in maternal blood pressure. These phenomena are believed to be associated with an increased rate of placental abruption. Hypeension, not hypotension, is associated with abruption. Acute hypotension can, however, cause fetal distress if untreated and may result in a similar fetal hea rate tracing to that associated with an abruption. Similarly, pre-eclampsia with elevated blood pressures is associated with abruptions. Ref: Cunningham F.G., Leveno K.J., Bloom S.L., Hauth J.C., Rouse D.J., Spong C.Y. (2010). Chapter 35. Obstetrical Hemorrhage. In F.G. Cunningham, K.J. Leveno, S.L. Bloom, J.C. Hauth, D.J. Rouse, C.Y. Spong (Eds), Williams Obstetrics, 23e.