The failure rate for typical use of birth control pills is 7%. For every million women taking pills, 70,000 unplanned pregnancies could occur in a year. According to the most recent data available, more than 6.5 million women ages 15 to 49 use oral contraceptives, leading to about 460,000 unplanned pregnancies. Even seemingly minuscule failure rates of IUDs and birth control implants can lead to surprises.Even seemingly minuscule failure rates of IUDs and birth control implants can lead to surprises. Some 4.8 million women use IUDs or implants in the U.S., leading to as many as 5,000 to 20,000 unplanned pregnancies a year.