Birth control pills are a popular and effective method of contraception but you may fall pregnant when you are on it. Picture: File
Birth control pills are a popular and effective method of contraception.

The birth control pill is effective if a person takes it correctly and does not miss any pill days. According to the Centers for Disease Control and Prevention (CDC), the pill is 99.7% effective with perfect use. This means that less than 1 out of 100 women who take the pill would become pregnant in one year.

However, there are some situations that can reduce its effectiveness and may sometimes result in unintended pregnancies. Here is a list of three reasons you may fall pregnant.  


Some medications including certain antibiotics, such as rifampicin, and anti-fungal drugs, such as griseofulvin can make your contraceptive  less effective.

Experts say backup contraception should be used while taking these medications and for 48 hours after finishing the course.


If you are obese you may be at risk of falling pregnant. Some research suggests that the birth control pill doesn’t work as well in very overweight women. 

If this affects you, speaking to your doctor about an alternative based on your current weight may get you a solution. 


Sometimes a person may be ill when they take the pill. When a person vomits, the pill can come back up, or they may not fully absorb it into their body.

Anyone who experiences vomiting shortly after taking the pill or for 48 hours after taking the pill should take another pill as soon as possible and then take their next pill as usual.