Emergency Contraceptive Pills and Menstrual Irregularities

Emergency contraceptive pill

Hello, I took emergency contraception on October 1st.
After my period started on October 7th, my menstrual cycle has been irregular for three months.
During this time, I missed my period on January 8th and it still hasn't arrived.

Mr. Hong, 20~29 year old female. Ask Date: 2016/01/09

Dr. Lin Manying reply Obstetrics and Gynecology

When was your last menstrual period? If it is a week late, please take a pregnancy test first.
Sometimes, emergency contraceptive pills can affect the menstrual cycle for a few months.
If your periods have been irregular for more than three months, please seek medical evaluation.

Reply Date: 2016/01/09

More Info

Emergency contraceptive pills (ECPs), commonly known as "morning-after pills," are designed to prevent pregnancy after unprotected intercourse or contraceptive failure. They are most effective when taken as soon as possible after the event, ideally within 72 hours, but some formulations can be effective up to 120 hours later. The two most common types of ECPs are levonorgestrel (Plan B One-Step) and ulipristal acetate (ella).
One of the side effects of taking ECPs is the potential for menstrual irregularities. After taking ECPs, some individuals may experience changes in their menstrual cycle, including earlier or later onset of menstruation, heavier or lighter bleeding, or even skipped periods. This is primarily due to the hormonal changes that the pills induce in the body.
In your case, you took an emergency contraceptive pill on October 1st, and then experienced your menstrual period on October 7th. However, you mentioned that your menstrual cycle has been irregular for the following three months, with a missed period in January. It is not uncommon for ECPs to disrupt the regularity of your menstrual cycle, especially in the months following their use.
The hormonal components in ECPs can lead to temporary changes in the hypothalamic-pituitary-ovarian axis, which regulates the menstrual cycle. This disruption can cause a delay in ovulation, changes in the endometrial lining, and alterations in the timing and flow of menstruation.
If you have missed your period for an extended time, such as in January, it is essential to consider other factors that could contribute to menstrual irregularities. Stress, significant weight changes, excessive exercise, and underlying medical conditions such as polycystic ovary syndrome (PCOS) or thyroid disorders can also lead to irregular periods.
If your menstrual irregularities persist or if you have concerns about potential pregnancy, it is advisable to take a home pregnancy test and consult with a healthcare provider. They can provide further evaluation and guidance, including checking for any underlying conditions that may be affecting your menstrual cycle.
In summary, while it is common for emergency contraceptive pills to cause temporary menstrual irregularities, it is essential to monitor your cycle and seek medical advice if you experience prolonged irregularities or other concerning symptoms. Your healthcare provider can help determine the cause and recommend appropriate management strategies.

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