For me the worst bit was all the free parenting magazines (full of adverts)
You know, it starts with the GP/midwifes handing you a Bounty bag at your first antenatal appointment, and before you know it you're subscribing to Emma's diary, the Pamper's newsletter and what not... Because, you know, who doesn't like free vouchers? And babies are expensive, everyone knows that, and also you could probably use some free parenting advice, and it's nice to feel part of a community. Oh and here comes the NCT! Etc.
And slowly you build that internal image of what a perfect mother should be like, making casts of her bump, giving birth naturally while listening to whale songs, booking baby photo shoots, breastfeeding while wearing the most fashionable baby sling, going to mother and baby yoga classes, bouncing back into her pre-pregnancy jeans, feeding on demand, sleep training, ...
Deep down, it's mostly all just marketing, really. All this "free advice" is trying to sell you something, whether it's a product, or "experiences", or "expertise"... Capitalising on the boundless love you feel for your baby (and on your self-doubt, and desire to excel), repackaging all these strong and confusing feelings into fancy (unatainable) aspirations thay they can easily sell back to you (just how many photographs and hand prints and foot prints of your newborn do you need, really? And how the fuck did we even survive before gender reveal parties?)
It's exploitative and psychologically harmful. But very lucrative, so no reason for it to stop? (just like women's fashion/beauty magazines are typically a cesspit of internalised misogyny)
Similarly, I believe a lot of modern regressive gender norms are being enforced through aggressive marketing, for purely financial reasons: e.g. the colour coding of baby/children stuff ensures that statistically, you sell more (can't so easily reuse heavily gendered items between siblings). Who cares if that's socially harmful? Profit!