Heather Corinna replies:

Ask my Mom: she sure did, and here I sit, the proverbial proof in the pudding. :)

Yes, you can. First-time intercourse doesn't change anything about your fertility. In other words, if someone has begun menstruating, that's because they first began ovulating. In other words, the first time a person ovulates -- when their ovaries release the first egg -- around two weeks later they'll have her first period. First ovulation and first menstruation tend to occur well before most for whom they occur choose to become sexually active.

And once that happens, someone can become pregnant. They don't need to have intercourse any given number of times for pregnancy to occur. High pregnancy risks are present from unprotected intercourse the first time, the third time, or the fifty-seventh time. Statistically, within one month of having intercourse without reliable birth control, around 25% of women will become pregnant, and within a year, around 85% will.

It should also be mentioned that since no method of birth control (save not having sex) is 100% effective, while reliable birth control can reduce that risk pretty greatly, it's also possible someone could become pregnant the first time they have intercourse even WITH protection, especially if a given method isn't used properly, or used for all direct genital contact.

Here's a few links for you and your classmates to give you more information on how the fertility cycle works, how pregnancy happens, birth control effectiveness rates, and when pregnancy risks are posed:

P.S. If you have a health teacher sending you to resources like this, and who is supporting you in researching answers to sexuality questions, you are one lucky student! Bring him or her an apple tomorrow, eh?