Can a woman fall pregnant if she had sex during ovulation and takes a morning after pill immediately after sex?

Pregnancy risk: Emergency Contraception such as Plan B One-Step is up to 89 % effective when taken within 72 hours (3 days) after unprotected sex. It can reduce chance of pregnancy by up to 95% if used within 24 hours. It continues to reduce the risk of pregnancy up to 120 hours (5 days) after unprotected sex, but is less effective as time passes. So there is still a chance.