I second Keith - get measured. It is generally held that men tend to have longer bodies and reach compared to their leg length while women have shorter bodies and reach with longer legs. Of course that doesn't apply to everbody or even every body
I have found it to be a problem to get a short enough reach even on my bikes carefully designed from my measurements and made by Roberts (South Croydon) generally held to be one of the best builders of bikes for women (I also tend to prefer sitting well back which doesn't help). And yet, I have had to put up with very short handlebar stems to fit my reach and that makes the bike quite lively. I have, however been pleasantly surprised by my titanium Enigma ordered through Pearsons in Sutton, which was based on my position on my blue Roberts, and which actually has a decent length handlebar stem and yet a short enough top tube for me. The problem with designing frames is that by changing the angle in one area it affects the whole bike and off the shelf women specific bikes tend to have very steep angles - well at least in the opinion of my mechanic - and it affects the way they handle and ride. Of course if they fit you, then it's fne - I just never have. Also some of them can be quite heavy and come with a saddle that looks like a sofa and as for the colours
Over the years things have improved, brakes made so that smaller hands can reach them easily, women's clothes
, acknowledgement of female specific designs etc but the cycling world, especially trade, is still male-dominated and in this country I have had difficulty getting hold of some products from overseas - so there is more choice for women but not always available, at least not easily. And men, as proved by some comments on here, don't always realise that female needs and problems can differ from men's - and how many women do you see working in a bike shop? I'll probably start a great outcry over some of my comments - and yes, I haven't a clue about actually frame designing and building but I am an expert on being a woman rider and what I feel comfortable riding!
OK, I'm going back to bed now...