Men are particularly likely to believe this. A lot of young blokes think that they'll be able to have intercourse as soon as their partner gets home from hospital. But this just isn't true.
You see, childbirth is a pretty traumatic process for a woman. Having a baby pass through her vagina is almost like having a small explosion go off inside her.
The delicate vaginal tissues are inevitably strained, bruised and torn – and it takes some weeks for these injuries to heal up.
Furthermore, childbirth involves considerable hormone changes – as well as emotional stresses. And as a consequence, very, very few women feel rampagingly sexy until a long time after they have given birth.
Therefore, it's important for both mother and father to realise that lovemaking may not go brilliantly in the first six months or so after the baby arrives. So be prepared – and be patient!