People who get migraines with aura—dots or zigzags in vision, or another sensory disturbance that typically occurs before the onset of a migraine—have long been told to avoid birth control that contains estrogen. The hormone has been linked to an increased risk of stroke in this population. How great is the risk, and what should you do if you’re one of the 25% of women of reproductive age who get migraines ? Here’s what doctors say.  The connection between migraines and stroke risk