the Effectiveness of 28-Day Birth Control Pills

28-day contraceptive pill

Hello, regarding the question about the contraceptive pill from yesterday, I chose to purchase a 28-day contraceptive pill.
The pharmacist told me that since this is my first time taking contraceptive pills, I need to finish all 28 days before achieving contraceptive effectiveness.
However, I have a question: the 28-day contraceptive pack contains only 24 active pills, while the remaining 4 are placebo pills.
If I have sexual intercourse after taking the 24 active pills, is there still close to a 90% effectiveness in preventing pregnancy?

Xiang, 20~29 year old female. Ask Date: 2017/02/25

Dr. Huang Jianzhong reply Obstetrics and Gynecology

Hello, regarding the question about the emergency contraceptive pill from yesterday, I chose to purchase a 28-day contraceptive pill.
The pharmacist informed me that since this is my first time taking contraceptive pills, I need to finish all 28 days before achieving contraceptive effectiveness.
However, I have a question: the 28-day contraceptive pill contains only 24 active pills, while the remaining 4 are placebo pills.
If I engage in sexual intercourse after taking the 24 active pills, will I still have close to a 90% contraceptive effectiveness?
Answer: Regardless of whether it is a 21-pill or 28-pill contraceptive regimen, they are primarily composed of two active ingredients: estrogen and progestin.
There are various products available on the market with different formulations and dosages.
In a 28-pill pack, the first 21 pills contain the active contraceptive ingredients, while the last 7 pills are non-active and typically contain vitamins or iron supplements.
The purpose of these placebo pills is to help you maintain the habit of taking one pill daily.
The packaging will indicate the days to prevent you from forgetting to take a pill or mistakenly taking two pills in one day.
The correct way to take the pills is to start on the fourth or fifth day of your menstrual cycle, taking one pill daily (generally recommended after dinner until bedtime).
If you realize you missed a pill yesterday when you are about to take today’s pill, you should take both pills at once (to make up for the missed dose), which will maintain the contraceptive effectiveness.
If you forget to take pills for two consecutive days, it may disrupt your menstrual cycle, and there is a possibility of pregnancy.
After finishing the first 21 active pills, you will likely get your period within about two days while taking the last 7 placebo pills, and the flow may be lighter.
For those with primary dysmenorrhea, menstrual pain may also be alleviated.
You should complete all 7 placebo pills before starting the next pack.
The first 21 pills and the last 7 pills usually differ in color.
After finishing the 21 active pills, continue with the 7 placebo pills to maintain the routine of taking one pill daily.
For the 21-pill regimen, after completing the 21 pills, you take a 7-day break before starting the second cycle, during which your menstrual period will occur.

Reply Date: 2017/02/25

More Info

When it comes to understanding the effectiveness of 28-day birth control pills, it's essential to clarify how these pills work and what the implications are for their use. The 28-day birth control pill regimen typically consists of 21 active pills (which contain hormones) and 7 inactive pills (placebo). The active pills are designed to prevent ovulation, thicken cervical mucus, and thin the uterine lining, thereby reducing the likelihood of pregnancy.

Effectiveness of 28-Day Birth Control Pills
1. Initial Use: For those who are starting birth control pills for the first time, it is generally recommended to take the active pills for at least 7 consecutive days before relying on them for contraception. This is because it takes time for the hormones to build up in your system and effectively prevent ovulation. If you start taking the pills at any time other than the first day of your menstrual cycle, it is advisable to use a backup method of contraception, such as condoms, for the first month.

2. Understanding the Placebo Pills: The last 7 pills in a 28-day pack are inactive and do not contain hormones. These pills are included to help maintain the habit of taking a pill daily and to allow for a withdrawal bleed that mimics a menstrual period. Importantly, the effectiveness of the birth control does not diminish during this week of placebo pills. The hormonal effects from the active pills continue to provide contraceptive protection throughout the entire cycle, including during the placebo week.

3. Effectiveness Rates: When taken correctly, the effectiveness of birth control pills can be as high as 99%. However, typical use, which accounts for missed pills or incorrect usage, results in an effectiveness rate closer to 91%. This means that if you take your pills consistently and correctly, you can expect a very high level of protection against pregnancy.

4. Sexual Intercourse During the Placebo Week: If you have taken all 24 active pills correctly and then engage in sexual intercourse during the placebo week, you still maintain a high level of contraceptive effectiveness. The hormones from the active pills remain in your system and continue to prevent ovulation.

5. Missed Pills: If you miss a pill, especially during the active pill phase, it can reduce the effectiveness of the birth control. If you miss one active pill, you should take it as soon as you remember and continue taking the rest of the pills as scheduled. If you miss two or more pills, you may need to use a backup method of contraception for the next 7 days.

Conclusion
In summary, if you are using a 28-day birth control pill regimen and have taken all 24 active pills correctly, you can expect to have a high level of protection against pregnancy, even during the placebo week. If you have any concerns about your specific situation or if you experience any unusual symptoms, it is always best to consult with a healthcare provider. They can provide personalized advice and ensure that you are using your birth control method effectively. Remember, consistent and correct usage is key to maximizing the effectiveness of birth control pills.

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