Welcome to the forum.
I assume you are asking about the most popular concealed carry firearm used by women? This is a loaded question. To make a bad analogy, what is the most popular car for women? Now, that we have that out of the way, this forum has a sub forum, called
Women & Guns, that specifically focuses on such issues. You may find interesting discussion threads in this sub forum that will help you.
Women carry all kinds of handgun calibers across the spectrum, including .38 Special +P or .357 Magnum revolvers, or .380 ACP, 9mm, .40 S&W, .45 ACP or 10mm semi-automatic handguns. Women also carry all kinds of handgun sizes, including snub-nose revolvers and single-/double-stack semi-automatic handguns. A number of firearms instructors tell women exactly the same thing that they tell man, carry a firearm that you can handle and that gets the job done.
Why do you ask? Are you looking for a handgun to carry? If yes, what is your level of expertise/training and how do you plan to carry the handgun?