"For example, they might be monitored for side effects of the pill and may be more likely to be screened for disease than non-users."
Also, the researchers didn't assess risk of death according to the type of hormone used in the pills the women took.
Hannaford cautioned that contraceptive choices should be based on contraceptive effectiveness, acceptability, and ease of use, among other factors -- not possible reductions in disease later in life.
"I would never recommend that someone use the pill simply to reduce their risk of disease later in life," he said. "However ... if the choice is the pill, this decision does not increase a woman's risk of long-term death. Indeed it may even have some benefits."