I know you're probably looking for a lighthearted response, but I'm afraid my thing to change would be the attitude of others towards pregnancy. There's a serious under appreciation of what women go through and this enforced 'martyr' attitude drives me bonkers.
Pregnancy is fucking hard, exhausting and deeply uncomfortable yet we can't complain (someone always trots out the 'some women would love to be pregnant', which I'm aware of, I have been one of them, but its an exceptionally unhelpful thing to say to someone in pain) we have to emit rainbows and fucking sunshine all the time.
In the place I worked in my 1st pregnancy, a colleague was pregnant at the same time as me. I was never sick first time but she had horrendous sickness, and vomited 8 times a day for 32 weeks. The sneery attitude of others in the team because she took a few sick days was disgusting. One twat man even hailed it as sexist that she could take pregnancy related sickness 
if you had any other condition where you were sick that much and often I expect other people would be sympathetic. But pregnancy is different.
I'm currently 5 months pregnant. I've had horrendous sickness (although it's getting better), Inhave a huge bump which makes me very uncomfortable, work 3 days a week, have a toddler, have had awful constipation and this week I've been off work because I've had haemorrhoids the size of plums and could barely walk let alone sit down. My SIL came round the other night and I was stood up in the kitchen and asked DH if he'd get me a water. The tap wasn't far away but he was closer and moving was agony due to plum piles 
. SIL commented about can you not do it yourself (TBF in a lighthearted way) and when I said no I'm carrying his baby he can at least get me a water (again lighthearted) she said "oh fuck off, honestly as if pregnancy is an excuse to be that bloody lazy". she has been pregnant herself and had a difficult pregnancy with sickness. Bitch.
I replied "fuck off yourself" (NOT lighthearted) and waddled out to go and lie down on my front
I strongly suspect this attitude is because women are the ones who get pregnant. I reckon if men got pregnant, morning sickness would be a sacrament, maternity
leave would be paid in full for a year and start at 12 weeks pregnant, and there'd be special tax funded helpers to rally round them until birth 
I find the same attitude once you've given birth, the "as long as baby is ok that's what matters" line - no actually I'm bloody important too, I'm not just a vessel that conveniently carries the baby and when my job is done, to hell with me - I'm a human, it's been hard work and I deserve care and support too. After I had my DD my husband's family visited hospital when she was 12 hours, picked her up and pissed about, I swear the only thing I got told was "God you look awful Pinky!" (Well yes I've lost 4 pints of blood as you know of course I fucking do) Not even a "how are you".
Sorry, rant over, it just pisses me off (can you tell? )