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Pregnancy and Birth Control 101

In order for a woman to get pregnant, three things have to happen:

  1. Ovulation
  2. Fertilization
  3. Implantation

Even if all of these steps go perfectly, there is no guarantee that a woman will remain pregnant. But let’s pretend she does remain pregnant and that it’s an unplanned, undesired pregnancy. So she goes to the doctor… like me, for example:

“Hello, I understand you’re pregnant.”
“How are you feeling about this news?”
“I don’t want to be pregnant.”
“OK, I understand. Please let me take the time to explain all of your options with this pregnancy. You may continue the pregnancy such that you will have a new baby in your family, you may continue the pregnancy and when you give birth place the baby in adoptive care, or you may end the pregnancy by having an abortion.”

This is a simplified version of how I personally counsel all of my patients who are newly pregnant with an unexpected pregnancy about which they are uncertain. (Note: women who answer the first question with “I’m very excited and can’t wait to have my baby!” do not receive counseling on the other options for obvious reasons.)

But, wait a minute! If people use birth control, there should be no such thing as an unplanned pregnancy!

Ah, if only more than just death and taxes were 100% in this world…

BIRTH CONTROL: HOW it works and how WELL it works

Methods that prevent Step #1: Ovulation

  • Nexplanon implant: >99% effective with typical use
  • DepoProvera injection: 94% effective with typical use
  • The Patch, the Ring, and the Pill (AKA combined oral contraceptive pills): 85% effective with typical use
  • Lactational Amenorrhea Method (breast feeding): 98% effective with perfect use in first 6 months postpartum
  • Emergency Contraception (Plan B, ella): the sooner after unprotected intercourse the better! 56-89% effectiveness, though studies are limited. It is ineffective if ovulation has already occurred, thus it is NOT an abortifacient

Methods that prevent Step #2: Fertilization

  • Sterilization (male and female): >99% effective with typical use
  • Mirena IUD (progesterone): >99% effective with typical use
  • ParaGard IUD (copper): >99% effective with typical use
  • Condoms: 80-90% effective with typical use
  • Natural Family Planning methods (withdrawal, calendar, basal body temperature): 75-80% effective with typical use

Methods that prevent (or disrupt) Step #3: Implantation

  • NONE

So, you see, no method works perfectly every time. Human beings are sexual beings and we will have sex. Even when we do everything right to prevent an unplanned pregnancy, our technology is not such that it can be prevented 100% unless one is not sexually active. But what’s the fun in that?

For more info, check out the links on the right under “Knowledge is Power.” Also, the CHOICE Project out of Washington University in St. Louis has a great video on the different methods and how to use them!

Resources: Contraceptive Technology by Hatcher et al, Practice Bulletins by the American College of Obstetricians and Gynecologists