I'm 31 weeks tomorrow and have had my son's diaper bag ready for a few weeks. I put new born and 0-3 months clothes in since I don't know how big he will be, socks, hat's, take home outfit,blankets, receiving blankets in case of spit up, diaper cream, wipes, diapers(some hospitals provide you with diapers), mitts for scratching. Don't need too much since you won't be staying long. Just the every day things. As for your bag. Comfy clothes for after the baby, nursing bra if you are breast feeding, breast pads, underwear and I mean like granny panties since you basically wear a diaper after you have a baby, shower things, tooth brush, too paste, phone,charger, camera, lip chap, money. That's a start. You can put in or take out things too
I will be packing a hospital bag this weekend, about to hit 33 weeks, I'll just put some baby stuff in my bag. Will have a couple comfy (and nursing) shirts and bottoms for both me and hubby (also underwear for hubby). Toiletries: hairbrush, toothbrush, chapstick, toothpaste, deodorant etc. A couple onsies for baby and a going home outfit, also one blanket for baby to go home with. Phone charger, a robe (great to have in case you get cold, but easy for nursing too), and birthplan. Things I know I won't need because our hospital provides them: giant granny panties for me including pads, blankets for baby, extra clothes for baby, diapers, wipes, baby hat.
My first baby I brought a lot more stuff and found it just took up space and was totally unnecessary, so I'm scaling back this time. You REALLY don't need much while you're there. Hubby and I did grab out own pillows too before we left for the hospital, I'm glad we did that.
I had 3 kids already and I'm on my 25th now. I'm just putting toothbrush toothpaste brush deodorant and a outfit for the baby , socks and a warm blankit that's it the rest the hospital provides.