A pregnant woman's life is always in danger, there are many conditions and diseases she can suffer from because of the pregnancy, and women still die in child birth even in this new modern age of medicine.
In both of my pregnancies I had forgot thename now someone else might know it, had to do with protein in my body, and my life as well as my children's lives were in danger. The girl next door to me in the hospital was there becasue she had a condition, again don't remember the name, that is common and puts both lives in danger.
http://www.medicalnewstoday.com/articles/81318.php
lots more sites like this one, want info look it up.