Hello,
Emergency
contraception (EC) can prevent up to over 95% of pregnancies when taken within 5 days after intercourse.
EC can be used in the following situations:
unprotected intercourse, concerns about possible
contraceptive failure, incorrect use of contraceptives, and sexual assault if without contraception coverage.
Emergency contraceptive pills prevent
pregnancy by preventing or delaying ovulation and they do not induce an abortion.
Drugs used for emergency contraception do not harm future
fertility. There is no delay in the return to fertility after taking ECPs.
So, to answer your query there is a probability of pregnancy even after taking EC, so, to confirm your doubt you should get a Pregnancy test done and consult a doctor if your periods are delayed even after negative contraceptive pills.
Hope I have answered your query. Let me know if I can assist you further.
Take care
Regards,
Dr Kalpajit Banik, Emergency Medicine Specialist