The editing of Wikipedia is done by volunteers. And there are not many women among these volunteers, in fact 90% are men. Not surprisingly, this has an effect on the content.
There are several efforts to get more Women in Science represented on Wikipedia.
For example, in France, there is a series of events, arranged by the History of Science Library together with Cité des Sciences.
Other events, called "edit-a-thon"s are held by for instance the Royal Society (in London), see here.
Or att the Smithsonian Institute (Washington DC), see here.
We would like to encourage everyone to try to edit Wikipedia. Perhaps arrange an edit-a-thon to get both more women editors and more women in maths represented in this very influential online resource.