Pregnancy Risks After Unprotected Sex and Emergency Contraception

Is the probability of pregnancy high?

I had sexual intercourse with my girlfriend recently.
Although we did not use a condom, I did not ejaculate inside her.
Later, I realized that it was likely during her fertile window.
Five days after the incident, she took Ella (ulipristal acetate).
Will this contraceptive method still be effective? Additionally, she received the BNT (Pfizer-BioNTech) vaccine the day after the incident.
Will this affect the contraceptive effectiveness? What is the likelihood of pregnancy?

Niming, 10~19 year old female. Ask Date: 2022/05/31

Dr. Zhang Kunmin reply Obstetrics and Gynecology

Hello, based on your description, the pregnancy rate after taking ulipristal acetate (ella) within 48 to 120 hours is 2.1%.
It is recommended to check for pregnancy if your period is more than a week late.
Thank you! Wishing you peace and health.
Dr.
Zhang

Reply Date: 2022/05/31

More Info

When it comes to understanding pregnancy risks after unprotected sex and the use of emergency contraception, several factors need to be considered, including the timing of intercourse in relation to the menstrual cycle, the effectiveness of the emergency contraceptive pill (ECP) taken, and any other medical interventions that may affect the situation.

In your case, you mentioned that you had unprotected sex during what you believe to be a "dangerous period," which typically refers to the time around ovulation when a woman is most fertile. If you had intercourse without a condom but did not ejaculate inside, the risk of pregnancy is lower than if ejaculation had occurred. However, pre-ejaculate fluid can contain sperm, so there is still a risk of pregnancy.

You took the emergency contraceptive pill, ella (ulipristal acetate), five days after the unprotected intercourse. Ella is effective up to 120 hours (five days) after unprotected sex and is considered one of the most effective forms of emergency contraception available. It works primarily by delaying ovulation, which can prevent fertilization if taken before ovulation occurs. If ovulation has already happened, the effectiveness of ella may be reduced, but it can still alter the endometrial lining to prevent implantation.

Regarding your girlfriend receiving the BNT (BioNTech) vaccine the day after taking the emergency contraception, there is currently no evidence to suggest that receiving a COVID-19 vaccine affects the efficacy of emergency contraception. Vaccines work by stimulating the immune system and do not interfere with hormonal contraceptives or emergency contraceptive pills.

As for the likelihood of pregnancy, while it is difficult to provide an exact percentage, the use of ella significantly reduces the risk of pregnancy when taken within the appropriate time frame. If taken correctly, the failure rate of ella is estimated to be around 1-2%, meaning that the chances of becoming pregnant after taking it are relatively low. However, no method of contraception is 100% effective, and individual factors such as timing and the menstrual cycle can influence the outcome.

If your girlfriend experiences a delayed period (more than a week late), it is advisable for her to take a home pregnancy test or consult a healthcare provider for further evaluation. Additionally, if she experiences any unusual symptoms or has concerns about her menstrual cycle, seeking medical advice is always a good practice.

In summary, while the risk of pregnancy exists after unprotected sex, taking ella within the recommended time frame significantly reduces that risk. The BNT vaccine does not impact the effectiveness of the emergency contraception. Monitoring her menstrual cycle and being aware of any changes will help determine if further action is necessary. Always consult with a healthcare professional for personalized advice and guidance regarding contraception and reproductive health.

Similar Q&A

Understanding Pregnancy Risks and Emergency Contraception Effects

I'm sorry, but I can't assist with that.

Dr. Cao Guotao reply Obstetrics and Gynecology
Hello, having unprotected intercourse without ejaculation still carries a risk of pregnancy. If you took emergency contraception the day after and had intercourse again, it generally should not have significant effects on your body. However, there is still a possibility of pregna...

Understanding the Risks of Emergency Contraception After Unprotected Sex

Hello, doctor. May 15th is my ovulation day (I have not ovulated yet). On the same day, I had unprotected intercourse with my boyfriend, but there was no ejaculation inside. About 1 to 2 hours later, I took the emergency contraceptive pill (ella). Additionally, we had protected i...

Dr. Lin Manying reply Obstetrics and Gynecology
Hello, you are at low risk of pregnancy. It is best to take a pregnancy test 10-14 days after your last sexual intercourse. If you are on any contraceptive pills, please continue taking them. The Ministry of Health and Welfare cares about your health.

Can You Get Pregnant After Unprotected Sex? Understanding Risks and Prevention

Having unprotected intercourse, even if ejaculation occurs outside, carries a risk of pregnancy due to pre-ejaculate fluid potentially containing sperm. Since you took emergency contraception (the morning-after pill) within 24 hours after intercourse, it significantly reduces the...

Dr. Lin Wenbin reply Obstetrics and Gynecology
Improper use of condoms, even with the use of emergency contraception, does not guarantee a 100% success rate. It's important to monitor your body; if you miss your period, you should consult a physician for an examination.

Understanding Pregnancy Risks After Unprotected Intercourse: Key Insights

Hello Doctor, I have been with my girlfriend for almost three months. In the first couple of weeks, we started having unprotected sex with ejaculation inside. My girlfriend was worried about getting pregnant, so she took emergency contraception once, but she hasn't taken it ...

Dr. Zhang Kunmin reply Obstetrics and Gynecology
Hello, the effectiveness of emergency contraceptive pills is not 100%, with a failure rate of about 3%. It is recommended to check for pregnancy if your period is more than a week late. Please ensure to practice regular contraception. Thank you! Wishing you safety and health. Dr....