Incredibly there seem to be people who are blissfully unaware that women put on weight during pregnancy. Maybe it's a sad indictment of our education system or maybe people do still believe that babies arrive by storks to cabbage patches and thus cannot fathom why women let themselves go in such a dramatic fashion when they are expecting.

Always saying what no one is thinking, Anna Botting of Sky News asked when the Duchess of Cambridge emerged with her newborn baby: "Why does she still have a bump?" To which the whole of Twitter chorused "Because she had a baby yesterday!" Equally helpful was OK! Magazine's offering of a "post-baby weight loss regime" for Kate. This has prompted many, including Jo Swinson, the minister for women and equalities, to ask the media to rethink their attitudes towards birth and women's bodies.

For the media not to consider women's bodies public property would be an incredible day indeed. But for them to at least address some of the ignorance and damaging attitudes about what pregnancy does to women would be a start. Women are already ashamed enough about their post-pregnancy bodies to the point where we clearly have no idea what they even look like. They are hidden away and wrapped under loungewear until society decides they are allowed back out in public.

We should not be surprised that pregnancy changes the shape of women's bodies. Carrying and sustaining a watermelon-sized parasite is likely to result in some weight gain. At full-term a baby is on average seven to eight pounds, add to that a weighty placenta, amniotic fluid, a rather enlarged womb, increased blood volume (you have around 50% extra blood by the end of your pregnancy), bigger boobs, larger muscles to carry around all of the above and the necessary fat reserves needed for energy to move from the sofa to the toilet repeatedly.

You need rather a lot of energy for giving birth and you are then expected to be producing a fatty, white substance to sustain this spawn for at least six months after it has made its entrance into the world. The biggest challenge after birth for most women is actually finding time to prepare food and eat themselves, rather than subject themselves to a regime of punishment for allowing their body to healthily sustain a baby.

The truth is many women will never regain the shape they had pre-pregnancy and there is nothing wrong with this. Women's bodies can tell a remarkable story whereas there is nothing, absolutely nothing, even remotely interesting about dieting: I am already bored to tears by people endless babbling on about their 5:2 diet. But if you told me you had stretch marks in the shape of Keith Moon's face, then I'd be interested. That's worthy of conversation, not how you tend to get a bit peckish on a fast day.

Women are starting to emerge from the shadows and reveal their post-pregnancy bodies such as those captured by photographer Jade Beall. Some women ping back into shape, some don't; some have bigger feet than before, most have a softer tummy. But what each of them should do is marvel at what their body has done. How it rearranged itself, how it grew that extra skin, produced that extra blood, manufactured that milk, how it does mysterious things to your bowels.

Human reproduction is ridiculous and incredible in equal measure. It reminds us that we are mammals but with the ability to consider the profound implications of that. We should celebrate women's bodies in all their shapes and sizes not punish them for the weird and wonderful things they do.

• This article was amended on 30 July 2013. It had said in the second paragraph: "Kay Burley of Sky News asked when the Duchess of Cambridge emerged with her newborn baby. "Why does she still have a bump?" This comment was actually made by Anna Botting, also of Sky News.