I’m not saying that new parents make bad friends, by the way. In many respects, new parents make the best friends. They are wide open, hysterical, around during the day, awake at 2am, shameless about undoing their shirts in public, desperate for adult conversation and will always have snacks in their bag. They are ravenous for gossip; for conversation that doesn’t revolve around naps and nipples and nappies. But they are, undeniably, living on a slightly different plane.

In my book Holding The Baby, I call this The Partial Eclipse: the person is still there, their light is still shining as bright as ever, only most of that light is being temporarily absorbed by their child. When you are directly responsible for the survival of a tiny, helpless infant 24 hours a day, it can be tricky to do things like reply to text messages or catch a train. When we live in a society still largely designed by and for men: in the workplace, on public transport, in pubs, in seventh-story flats – it can be challenging to push your mothering body into public spaces. When you live along the very edge of life and death all day and all night, it can be a stretch to remember the details of someone’s kitchen renovation.

Instead of telling ourselves that having a baby won’t affect our relationships, it might be more helpful and more honest to talk about how they probably will. After all, getting a new partner, moving house, changing job and getting really into cycling can all affect your friendships, family and other relationships, so why on earth wouldn’t having a baby? You will almost certainly have to take a break from paid work, meaning you have less money and are therefore less able to do the things you did before. You may have different opinions on parenting styles. One of you might be experiencing fertility issues and find it hard to talk about the details of pregnancy and motherhood. You might need to move somewhere with more space, or close to your family or that smells slightly less of weed. You might become more anxious or start feeling like a Stepford wife or have nothing to talk about except the 14 videos of shark attacks you watched while feeding your baby at 3.14am. You might be touched out. Or desperate for someone – anyone – to stroke your hair.

The important thing is that this is a partial eclipse. It changes. It moves. As those babies learn how to sleep, how to push food into their own mouths, to be soothed by others, so their birth parent will simultaneously have more time to meet up, more of a short-term memory, more energy for the world. They will finish sentences and eat with two hands and keep their tops on and remember your address. Friendships – all relationships – are supple, subtle things. They can adapt or bloom or fade away or start anew. Since having a baby I have written four books, moved city, fallen out with people, bought a house, swam in the river, met new people, got married, taken on an allotment and bought a mobile barbecue. I do now have more money and more friends than I did when I was pregnant. That woman was right.

But I did lose some of both along the way.

Holding the Baby: Milk, Sweat and Tears from the Frontline of Motherhood by Nell Frizzell (Doubleday; £16.99) is out now.

“Having a baby completely reshaped my friendships, so why does no one talk about it?”