What are the chances of falling pregnant by having sex 7 days before ovulation?

I f not protected: with birth control pills, condoms or spermicidal foam, gel or vaginal egg, you could certainly get pregnant.

Ovulation ?: In a perfect setting sperm would not survive 7 days in your system waiting for an egg. However, how do you know for sure when your body quietly releases an egg. There are good models for predicting timing but women have become pregnant on any day of their cycle, including menses. You may be at less risk during some days but there is really no point where you can ignore BC to avoid pregnancy.

See below : Pregnancy is known to have occurred from sex on any and all days of the cycle. If you miss your period by 4-5 days do a home pregnancy test. If the result is negative repeat the test in 4-5 days unless you get a period by then. Practice contraception all the time, every time. Get HPV vaccine.