Death cases are rare. Not sure why it happens though. I was scared my first pregnancy, even said goodbye to my hubby lol. Silly me
A pregnant woman could get deep-vein thrombosis, it is slightly more common in pregnancy than other times. Deep-vein thrombosis can possibly lead to pulmonary embolism. But one would have to ignore the deep-vein thrombosis for a while, for it to develop into a pulmonary embolism. Since DVT is noticeable and hurts, unless the woman was in a place without medical care, the likelihood of death is not high.
Sweetheart, are you worried about dying in childbirth? They won't let you. :) Try not to worry.
Several things can cause it however it's not very common. If you have things like eclampsia or HELLP syndrome your BP can cause you to have a stroke, however the most common cause is hemorrhage and blood loss.