How deep is a vagina ?
First of all, i want to say the last study about the average vagina depth size is dated from 1929. In his book entitled “Atlas of human sex anatomy“, Robert Latou Dickinson stated that a 6 inches test tube was able to be hidden from daylight after entering it inside a vagina. Except this small information from Robert Latou dickinson, no other studies have been carried out to how deep a vagina is. There is a reason for it. It is not possible yet to artificially create the arousal state of a vagina. I heard about a magical pill that would trigger an aroused state but it is only experimental. Thus, we cannot really compare aroused vagina depth sizes between individuals. For instance, we cannot compare how deep a vagina is between Betty and Jessy. Betty may be very aroused during the test and Jessy may be slightly aroused during the test. Consequently, Jessy may not be able to insert so much length in her vagina. Nevertheless, Jessy may be theoretically able to insert much more length in her vagina. As per June 2011, no medical studies have been published about the depth of vagina. In other words, everything you may read over the internet are just speculations.
In fact, we really need to measure the vagina depth in arousal state in order to get accurate measurements because the vagina inner expansion during arousal. By the way the arousal state is different from vaginal behaviour during child labor. The vagina doesn’t behave in the same manner during sexual arousal and child labor. So, it is useless to compare both of those behaviours.