The study by Rahman et al., investigated the effect of consumption of arsenic contaminated tube well water on infant death and fetal loss in Bangladesh. The exposure was measured in terms of arsenic concentration in tube wells and the outcome was measured in terms of fetal loss and infant deaths. The subjects for this study were pregnant women and in all, 29,134 pregnancies were included in this cohort study.
Inclusion/exclusion criteria for subjects:
- Only the pregnancies that took place between 1991 to 2000 were included.
- The subjects were only from the Matlab region of Bangladesh.
- Only those subjects were included whose drinking water history could be found out.
- The subjects were excluded if the arsenic concentration in the tube well (used during the pregnancy) was not available.
Using these inclusion/exclusion criteria, only 29,134 pregancies qualified as sample subjects out of the total 51,500 pregnancies.
Hope this helps.