One of the most common questions people ask about birth control is:
“How well does this method actually work?”
The answer depends on the method and how you use it.
What is a failure rate?
Your healthcare team may talk about something called the failure rate, which is just another way of saying:
“Out of 100 people using this method for one year, how many are likely to get pregnant?”
Perfect Use vs. Typical Use
Every method has two effectiveness numbers:
Perfect use: When the method is used exactly right every single time
Typical use: How most people use a method in real life (missing pills, forgetting condoms, not using something every time, etc.)
Because real life isn’t perfect, typical use is usually less effective than perfect use.
Example: (“pulling out”)
Typical use: About 20 out of 100 people will get pregnant in a year
Perfect use: About 4 out of 100 people will get pregnant in a year
The difference shows how much everyday habits can affect effectiveness.
Comparing Methods to Using No Birth Control
It can be helpful to compare these numbers to not using any birth control at all.
Without any method, about 85 out of 100 people (85%) will get pregnant within one year.
Important note: This 85% number is based on studies of the general population, which often includes younger people with higher fertility.
For people who have had breast cancer, fertility may be lower because of age, treatments like chemotherapy, or other health factors. Still, pregnancy is possible, so birth control is important if avoiding pregnancy is the goal.