Why is the contraceptive pill only 99% effective? What makes it fail?
I got curious and decided to google it but couldn't find the answer and now it's bugging me. So say I am a healthy woman with no stomach problems or taking any other medication that can affect the effectiveness of the pill. I also take it as indicated and never miss a day. There is still a 1% chance of getting pregnant, right? Well, why?
The contraceptive pill is often described as being over 99% effective with perfect use, which means that if taken exactly as prescribed (at the same time every day, without missing doses), the risk of pregnancy is very low. However, the typical effectiveness rate is around 91% because, in real-life usage, people may miss doses or not take the pill consistently.

Even with perfect use, there are still a few reasons why the pill might not be 100% effective:

1. **Individual Variation**: Each woman's body can respond differently to hormonal contraceptives. Factors like metabolism, hormonal fluctuations, and individual biochemistry can affect how well the hormones in the pill work.

2. **Timing and Absorption**: The effectiveness of the pill relies on it being absorbed properly into the bloodstream. While most women take the pill consistently, factors such as gastrointestinal issues (even minor ones), changes in diet, or certain activities can potentially affect absorption.

3. **Hormonal Interactions**: While you mentioned not taking other medications that could affect the pill's effectiveness, it’s worth noting that some medications (like certain antibiotics, anti-seizure medications, and herbal supplements like St. John's Wort) can interact with the pill and reduce its effectiveness.

4. **Ovulation and Breakthrough Ovulation**: In rare cases, some women may still ovulate while on the pill, particularly if they are on a lower-dose formulation. Breakthrough ovulation can occur, leading to the
The contraceptive pill is only 99% effective because there is a small chance of it not being taken correctly or on time, or because of certain medical conditions or medications that can reduce its effectiveness. Additionally, if it is not taken consistently, it may not be effective in preventing pregnancy.