There are several reasons why our information about maternal deaths is so sketchy.
Gaskin
I M
IM
D002423:Cause of Death; D003644:Death Certificates; D005260:Female; D006801:Humans; D008428:Maternal Mortality; D011159:Population Surveillance / Q000379:methods*; D011247:Pregnancy; D015203:Reproducibility of Results; D014481:United States / Q000453:epidemiology