Freshman or Freshwoman

There is a slow but substantial trend of avoiding gender-specific nouns when either gender could qualify. "Chair" in place of "chairman/woman/person" is one example. If you wish to refer to women using terms usually reserved for men, then it's perhaps a good hint that you should start using a different term, which would include both the men and the women.

There are some explicitly gender-neutral terms for these, which for the moment are appropriate for informal speech:

• In British English: fresher.
• In American English: frosh.

In formal speech, I would tend to prefer constructions such as "first year Bachelor's student" — or just "first year" if it's clear from context.