Here is a list of the women that gave birth to the most children. Notice that it is only one page and the list stops at 20 which is just short of 19.
The list of lottery winners would fill a very large book and a list of current billionaires is many times longer. In other words, having 19 or more children is even more rare than other ultra-rare events. I think it is safe to say that 19 is in no way ‘normal’ no matter how you look at it.
The term ‘average’ doesn’t really fit with this question either. Neither the mean, median or mode works because a significant percentage of women have fertility issues or cannot conceive at all. You can’t have women having 30 kids to offset those that can only have a few or none because that isn’t possible. What does ‘average’ mean then? You would have to define it so that it is really asking whether those women that are biologically capable of having 19 children can pull it off? That is both circular and speculative. There are undoubtedly a few that can but the vast majority can’t.