This just in from a CBS news article…

It would appear from some preliminary research performed by Australian scientists that, as might be suspected, infertilitymay be a factor that’s driven by couple-specific physical incompatibilities.  Thus, a man may have fertility difficulties with one woman but not with others.

The crux of the problem appears to be in how the woman’s body reacts to the man’s sperm.  If her body is accepting of his particular sperm, she’ll enable his sperm to fertilize her eggs.  If her body isn’t accepting of his sperm make-up, natural conception will be more difficult.

This isn’t to suggest, of course, that any of this “denying or accepting” is happening on a conscious level.  Neither men nor women can innately control the way their bodies respond.  But it could lead to future fertility treatment options that, until now, haven’t been attempted.