There is a definite chance that any woman can get pregnant during here periods. Though the chances of pregnancy during periods are usually low during periods, they exist for all women. During periods, the chances of pregnancy are comparatively lower at the onset of a woman's period and increase just after her periods
You can read more about this here.
http://www.babyhopes.com/articles/pregnantduringperiod.html
If you have any other questions please feel free to ask.