A recurring topic of conversation among my jolly group of “mum friends” at the moment seems to be about whether or not to go for the third child. We all have two – a compact number, easy to transport, a sibling has been provided for the first, people will still invite you for lunch, etc – but we all seem to be obsessed with the idea of having more. Instead of just getting on with it, though, we talk about it in hushed voices as if more than two is somehow unnecessary, extravagant, indulgent and possibly unmanageable with all the pressures of modern life.