"Redundancy" is an interesting observation, islandtime. Like others, though, I found a dissonance with the line beyond redundancy. While others seem to be suggesting a crudeness, I think, I find it cowardly, crudeness perhaps a welcome alternative.

Which is to say that you are either spreading your legs or you are not. So why the apparent evasiveness, the apparent effort at some sort of political correctness? As you and others suggest, it would behoove the discerning reader to make sense of this line which, if not a mistake on the poet's part, is critical enough that it is made to stand out.

We can disregard the notion of a birthing, as birthing is at least ordinarily thought of as giving rather than receiving, of expulsion rather than reception. So (and if you are a woman this perhaps bothers you as much as any notion of redundancy or dissonance) is the poet suggesting that the poet/subject is in a position of docile acceptance? Or, not harsh, in a position to allow love and the beginning of a birthing, creation?

A curious line.

Take care,

Joe