Blame modern contraception. For the last 3 generations most families have had on average no more than one daughter so there's a good chance today's new mums have never had the experience of watching a mum/aunt/sister going through pregnancy. Contrary to folklore girls aren't born with an instinctive knowledge of what goes on, it has to be learned. Small wonder they're scared to death and think they're dying when the little chap starts turning somersaults inside them.