How Long to Take Birth Control Pills for Effective Contraception?

Emergency contraceptive pills

Hello Doctor, I have been consistently taking the contraceptive pill, Mestranol, since March of this year.
I stopped taking it for a month in August.
While I was on the pill, my menstrual cycle was very regular at 28 days.
My period in June was from June 29 to July 3, and in July it was from July 27 to July 31.
After stopping the pill in August, my cycle lengthened to about 32 days, with the first day of my period on August 28.
This month, I plan to resume taking the contraceptive pill.
I took my first pill on the evening of August 31, which was the fourth day of my period, and I will continue to take one pill every evening.

I would like to ask the doctor: how many more days do I need to take the pill to achieve complete contraceptive effectiveness? My boyfriend and I are accustomed to not using condoms, and we occasionally have ejaculation inside.
To ensure safety, I would like to know how many more days of consistent pill-taking are necessary for reliable contraceptive protection.
Additionally, since my cycle has been very regular while on the pill, does this indicate that the medication is effective? Is there still a chance of pregnancy with occasional ejaculation inside?

Xiao Qing, 10~19 year old female. Ask Date: 2019/09/01

Dr. Huang Jianzhong reply Obstetrics and Gynecology

Since March of this year, I have been consistently taking the contraceptive pill, Meisilon.
In August, I stopped taking the pill for one month.
While I was on the medication, my menstrual cycle was very regular at 28 days.
My period in June was from June 29 to July 3, and in July, it was from July 27 to July 31.
After stopping the medication in August, my cycle lengthened to about 32 days, with the first day of my period being August 28.
This month, I plan to resume taking the contraceptive pill.
I took my first pill on the evening of August 31, which was the fourth day of my period, and I will continue to take one pill every evening.
I would like to ask the doctor: how many more days do I need to take the pill to achieve complete contraceptive effectiveness? My boyfriend and I are accustomed to not using condoms, and we occasionally have ejaculation inside.
To ensure safety, how many more days of consistent use do I need for effective contraception?
Answer: 7 days.

Additionally, I would like to ask, since my cycle has been very regular after taking the pill, does that indicate the medication is effective? Is there still a chance of pregnancy with occasional ejaculation inside?
Answer: There is no chance of pregnancy.

Reply Date: 2019/09/01

More Info

When it comes to the effective use of birth control pills, understanding the timing and consistency of taking the medication is crucial for ensuring optimal contraceptive effectiveness. Birth control pills, such as the one you mentioned (美適儂), typically require a specific regimen to be effective in preventing pregnancy.

Generally, when starting a new pack of birth control pills, it is recommended to take the pills consistently for at least seven consecutive days before relying on them for contraception. This is particularly important if you are starting the pills after a break, as you have done in August. Since you resumed taking the pills on August 31, you should continue taking them daily for at least seven days to ensure that you have adequate contraceptive coverage. After this initial week of consistent use, the pills should provide effective contraception, assuming you take them as directed.

It's important to note that the effectiveness of birth control pills can be influenced by several factors, including missed doses, interactions with other medications, and gastrointestinal issues (such as vomiting or diarrhea). If you miss a pill, the general guideline is to take it as soon as you remember, and if it's close to the time of your next dose, skip the missed pill and continue with your regular schedule. In cases of missed pills, additional contraceptive methods, such as condoms, may be advisable for at least seven days.

Regarding your menstrual cycle, the regularity you experienced while on the pills indicates that they are working effectively to regulate your hormones and menstrual cycle. However, when you stopped taking the pills, your cycle lengthened, which is not uncommon as your body readjusts to its natural hormonal balance. The variability in cycle length can occur when transitioning off hormonal contraceptives, and it may take some time for your cycle to stabilize.

As for the question of whether occasional unprotected intercourse (内射) while on the pill poses a risk of pregnancy, if you are taking the pills correctly and consistently, the risk of pregnancy is significantly reduced. Birth control pills are over 99% effective with perfect use, meaning that if taken exactly as prescribed, the chances of becoming pregnant are very low. However, with typical use, which accounts for missed pills or inconsistent use, the effectiveness drops slightly, but it still remains a reliable form of contraception.

In summary, to ensure effective contraception after resuming your birth control pills, continue taking them daily for at least seven days. After this period, you can rely on them for contraceptive protection. If you have any concerns about missed doses or interactions, or if you experience any unusual symptoms, it is advisable to consult with your healthcare provider for personalized guidance. Additionally, if you are considering alternative contraceptive methods or have questions about your reproductive health, discussing these topics with a healthcare professional can provide you with the most accurate and tailored advice.

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