First I would like to ask what is your e-mail address?

When is a girl most fertile? How well does birth control shot's work? Also how long after the shot do they take effect?

The Ask The Doc email address is ask.thedoc@wwu.edu.

Women are most fertile approximately 12 to 16 days before their next period, with ovulation most likely to occur 14 days prior to the next period. Obviously, that is something that cannot be calculated ahead of time with precision, because you don't always know when the next menses will be! So impending ovulation can be detected through a variety of means, including a spike in basal body temperature, changes in cervical mucus and some over the counter ovulation detection kits.

Theoretically, injectable contraception (Depo Provera and Lunelle) should be effective if given right after a menses, but our advice is to use condoms for at least one month in case a "break through" ovulation occurs while adjusting to the synthetic hormones.