Effectiveness of Ulipristal Acetate After Ovulation: What to Expect

Emergency contraceptive pill

If a physician has unprotected intercourse on the night of ovulation and takes the emergency contraceptive pill Ulipristal acetate (Ella) within one hour, the effectiveness of the medication is estimated to be around 85% in preventing pregnancy.
The efficacy may vary depending on individual factors, but taking the pill as soon as possible after unprotected intercourse maximizes its effectiveness.

Yu, 20~29 year old female. Ask Date: 2019/11/27

Dr. Huang Jianzhong reply Obstetrics and Gynecology

On the night of ovulation, engaging in intercourse with ejaculation and taking the emergency contraceptive pill Ulipristal acetate within one hour, what is the effectiveness and success rate of the medication? Answer: 90-95%.

Reply Date: 2019/11/27

More Info

Ulipristal Acetate, marketed under the brand name Ella, is a selective progesterone receptor modulator that is used as an emergency contraceptive. It is designed to prevent pregnancy after unprotected intercourse or contraceptive failure. The effectiveness of Ulipristal Acetate is influenced by the timing of administration in relation to the ovulation cycle.

When taken on the day of ovulation, Ulipristal Acetate can still be effective, but its efficacy may be reduced compared to when it is taken before ovulation. Studies suggest that Ulipristal Acetate is most effective when taken during the luteal phase, which is the time after ovulation and before menstruation. However, it can still inhibit or delay ovulation if taken shortly before or during ovulation, which is crucial for its contraceptive effect.

In terms of success rates, research indicates that Ulipristal Acetate can reduce the risk of pregnancy by approximately 85% when taken within 120 hours (5 days) after unprotected intercourse. However, the effectiveness is highest when taken as soon as possible after the event. If taken on the day of ovulation, the success rate may be lower than if taken earlier in the cycle, but it is still a viable option.

The exact percentage of effectiveness when taken immediately after intercourse on the day of ovulation can vary based on individual factors such as body weight, hormonal levels, and the timing of ovulation. Generally, the effectiveness is estimated to be around 60-70% in this scenario, but this is a rough estimate and can vary.

It is also important to note that Ulipristal Acetate does not terminate an existing pregnancy; it works primarily by preventing ovulation or fertilization. If ovulation has already occurred and fertilization has taken place, the medication is unlikely to be effective.

For those considering using Ulipristal Acetate, it is advisable to consult with a healthcare provider to discuss the timing of administration, potential side effects, and any other contraceptive options that may be more suitable for long-term use. Additionally, it is essential to understand that emergency contraception should not be used as a regular contraceptive method, and regular contraceptive methods should be considered for ongoing protection against unintended pregnancy.

In summary, while Ulipristal Acetate can still be effective when taken on the day of ovulation, its efficacy may be reduced compared to earlier administration in the cycle. The success rate is estimated to be around 60-70% in this scenario, and it is crucial to seek guidance from a healthcare professional for personalized advice and recommendations.

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