https://www.cbc.ca/news/canada/calgary/premature-baby-dies-of-measles-in-alberta-outbreak-s-1st-death-1.7649692
The pregnant mother likely contracted measles, a significant cause of miscarriages/abortions/stillbirths and preterm birth. Preconception MMR (a live attenuated vaccine) provides the protection to prevent measles deaths, especially to pregnant patients and preterm babies who have weaker immune systems than normal.
There are currently 1,914 cases of measles reported in Alberta since this March, with 152 hospitalized (8% of cases) and 15 requiring ICU care.