A better option than reminders is to view them in the feeds screen as a notification.

Install the app called "Organizer Feed" (free from Nokia Store), refresh feed screen, when birthdays pop up in the feeds screen, tap and hold on one of them, click settings, then click the Organizer Feed button. Go in calendar settings and click birthdays. Now you'll get a lot of options to tweak how you can view the birthdays and how they appear.