Be a post whore!

[DanaC]

I think it's more subtle than that, myself. I think that pregnancy is basically proof positive of promiscuity (in society's eyes). As long as people are sleeping with each other and nobody's pregnant, it is private. As soon as a women is pregnant it brings it out into public view. It also transforms the woman instantly, in society's eyes, from free individual, to responsible carer. We want our responsible carers to be morally acceptable and thoroughly intergrated into our social norms.

A pregnant teenager or adult one night stand offends (even if only at a vestigial level) society's norms and so the pregnant woman is automatically being judged immoral and therefore potentially dangerous. We are sophisticated enough to deal with women having sex, but we are not yet sophisticated enough to withhold judgement on a mother-to-be.

Like I say, all at a fairly vestigial level.