Birth Control Basics

  Roughly six out of every ten pregnancies in the United States are unplanned, according to the Institute of Medicine. Many experts think this high rate of unintended pregnancies results from a lack of knowledge about contraception. But it’s important to remember that no form of birth control is 100% effective at preventing pregnancy. Here are the stats on effectiveness.

  Tubal ligation and vasectomy procedures are probably the most effective means of contraception, preventing pregnancy more than 99.5 percent of the time. Intrauterine devices, or IUDs, fail to prevent pregnancy in roughly 1 to 2 percent of women who use them for a year. For women injection of birth control hormones or implantation of hormones has just about the same effectiveness, but these hormones carry an increased risk of developing dangerous blood clots. So do oral contraceptives, and the pills are a bit less effective at preventing pregnancy. About 5 percent of women taking oral contraceptive for one year will conceive inadvertently. Typical condom use has an unintended pregnancy rate of about 14 percent per year, and the conception rate for women using the vaginal sponge and diaphragm is about 20 percent.

  The emergency birth control method ‘Plan-B’, which is often called the morning after pill, prevents pregnancy in roughly 75 percent of cases if taken within 72 hours of unprotected sex, but it is most effective if started within 24 hours. -Sean Kenniff, MD