Not essential "in between"; while in the fertility sentence the apparent phrase to me is "with". However there may be explanations to work with "across" with "gender"; for your commence, it permits "gender" to get a non-depend noun, which "concerning" does not.永康區 東區 北區 中西區 安平區 安南區 善化區 新市區 歸仁區 仁�