Objective
In countries with limited vital registration data, maternal mortality levels are often estimated using siblings' survival histories (SSH) collected during retrospective adult mortality surveys. We explored how accurately adult deaths can be classified as pregnancy related using such data.

Method
The study was conducted in a rural area of south-eastern Senegal with high maternal mortality, Bandafassi. We used data from a demographic surveillance system (DSS) in this area to identify deaths of women at reproductive ages between 2003 and 2009 and to locate the surviving adult sisters of the deceased and interview them. Siblings' survival histories were linked at the individual level to death records, and verbal autopsy data obtained by the demographic surveillance system. We compared the classification of adult female deaths as pregnancy related or not in interviews and DSS records.

Results
There were 91 deaths at reproductive ages in the Bandafassi DSS between 2003 and 2009, but only 59 had known surviving sisters. Some deaths were omitted by respondents, or reported as alive or as having occurred during childhood (n = 8). Among deaths reported both in the SSH and DSS data, 94% of deaths classified as pregnancy related in the DSS data were also classified as such by siblings' survival histories. Only 70% of deaths classified as not pregnancy related in the DSS data were also classified as such by siblings' survival histories.

Conclusion
Misclassifications of pregnancy-related deaths in retrospective adult mortality surveys may affect estimates of pregnancy-related mortality rates.