ooh this thread is so interesting.
As to why have children/babies - because they smell amazing, are delightful and entertaining, and I absolutely HAD to have at least one. I'm crazy about babies and children - am a very proud aunt to lots of little ones, and felt sure from an early age I wanted to be a mother. DH was even more broody, and we were both upfront about it from the moment we met (weirdos, I know!) so that was simple. There is no reason to do it, and certainly no one should. But we just had to, IYSWIM.
The health stuff is important - DS is very healthy so far, we've been lucky, but I spent the entirety of my first trimester either asleep, being exhausted, or feeling extremely sick. DH had to do all the food stuff (and wasn't allowed to even fry an onion some days!) and all the laundry (I couldn't cart it up and down 3 flights of stairs) and clean the bathroom (I couldn't bend without throwing up) - and I had a relatively uncomplicated pregnancy - nothing out of the ordinary. If he had been a bastard about it then - if he had so much as murmured, frankly - I would have lost my shit about it, because I had to be pregnant and he didn't and I hated being pregnant. I went to bed at around 6.15 most evenings (having got home at 5.45) and we barely ever had sex or even cuddled, I just felt too awful. DH had to work hard to not feel rejected and unloved and the unpaid housemaid, I think.
Second trimester was a lot better, but I had constant heartburn. Third trimester I was just a big puffy hot thing with a raging horn (that's what the men like, you know, enormous women who cry at the drop of a hat and then try to jump their bones...) - I had to struggle with my OWN internalized patriachal values, too. "I'm hideous" and "What if I'm a bad mother", etc.
It just so happens that DH was glorious at that stuff, and either honestly did find me attractive all the time I was pg or is a damn good liar - but yeah, it's tricky. He did a lot more housework when I was pg than he ever did before, because I simply couldn't - in the last 2 weeks I was so swollen up I couldn't grip things properly - and that was a good inkling that he'd do a fair share in the following weeks.
Second whoever says get your DH to go to 4 days at once, and you get a day to be your own self. I went back to work VERY early 3 days a week, and DH did the childcare drop off - that helped keep things on an even keel, I think. I also had a "I put food in, you change nappies" deal with him for the first 3-6 months, which gave him a special role. . . and therefore an area of expertise. When I wasn't BFing I gave him the baby... tried not to tell him how to do it...
It's very hard.