Can Changing the Time of Birth Control Pills Affect Pregnancy Risk?

Changing the timing of oral contraceptive pills?

Hello, doctor.
I am currently taking Aygestin.
I started taking the medication on the fifth day of my menstrual cycle, following a regimen of 21 days on and 7 days off.
I have now completed four packs of the medication.
For the first three months, I took it around 9 AM, but this new pack I started taking at 11 PM.
I have been consistent with my dosing.
My last menstrual period started on June 14, so I began this new pack on the night of June 19 at 11 PM.
I had sexual intercourse with my boyfriend on June 22, using a condom.
Although I have read that changing the time of taking the new pack is acceptable, I would like to ask if there is a chance of pregnancy.
Thank you.

Niming, 10~19 year old female. Ask Date: 2018/06/23

Dr. Huang Jianzhong reply Obstetrics and Gynecology

I have been taking Aygestin, starting the first time on the fifth day of my menstrual cycle, taking it for 21 days and then stopping for 7 days.
I am currently on my fourth pack of medication.
For the first three months, I took it around 9 AM, but this new pack I started taking at 11 PM.
I have been consistent with my dosing.
My last menstrual period started on June 14, so I began the new pack on the evening of June 19 at 11 PM.
On June 22, I had sexual intercourse with my boyfriend using a condom.
Although I read that changing the time for the new pack is acceptable, I would like to ask if this could result in pregnancy.
Answer: This will not result in pregnancy.

Reply Date: 2018/06/23

More Info

Changing the timing of when you take birth control pills can potentially affect their effectiveness, but it largely depends on the specific type of pill you are using and how consistently you take it. In your case, you are using a combined oral contraceptive pill (often referred to as the "combination pill"), which contains both estrogen and progestin. These pills are designed to be taken at the same time every day to maintain stable hormone levels in your body, which is crucial for preventing ovulation.

When you switch the time of day you take your pill, as long as you are still taking it consistently and within a reasonable time frame (typically within a few hours of your usual time), the effectiveness should not be significantly compromised. However, if you take it too late or miss a dose, this could increase the risk of ovulation, which in turn raises the risk of pregnancy.

In your situation, you mentioned that you switched from taking the pill in the morning to taking it at night. If you have been diligent about taking your pill every day without missing any doses, the risk of pregnancy remains low. Additionally, you used a condom during intercourse, which provides an extra layer of protection against pregnancy. Condoms are effective when used correctly and consistently, and they also offer protection against sexually transmitted infections (STIs).

It's important to note that while the combination pill is highly effective when taken correctly, no contraceptive method is 100% foolproof. The typical failure rate for combination pills is about 7% with typical use, but this rate drops to less than 1% with perfect use. Since you have been taking your pills as directed and used a condom, your risk of pregnancy is quite low.

If you have concerns about the timing of your pill or any potential interactions with other medications or health conditions, it is always a good idea to consult with your healthcare provider. They can provide personalized advice based on your medical history and current situation.

In summary, changing the time of day you take your birth control pills can affect their effectiveness, but as long as you take them consistently and correctly, the risk of pregnancy remains low. Using condoms adds an additional layer of protection, further reducing the likelihood of unintended pregnancy. If you have any doubts or experience any unusual symptoms, do not hesitate to reach out to your healthcare provider for guidance.

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