Birth control works in one of three ways: (1) interfering with the menstrual cycle, (2) blocking sperm from getting into the uterus, or (3) preventing implantation of an embryo in the uterus. That’s it. So, to understand how each method works, we first need to understand: (1) how the normal menstrual cycle works, (2) how sperm get into the uterus (I’m sure you’ve already figured this one out), and (3) how babies form in the womb. 

Thus, making an informed decision about birth control requires a basic understanding of how reproduction works. We’ll try to make things simple, and keep medical jargon to a minimum, discussing only the relevant points. Hopefully, by the end, you’ll feel much more comfortable with the complex biological processes that happen inside us every day.

If the science of reproduction doesn’t interest you, and you just want to know your birth control options, feel free to skip ahead to the next section. You can always come back here for clarification later.

Now, let’s dive into the most intimidating subject of all: the menstrual cycle.