Disclosure: Affiliate links are used in this post, but all thoughts and opinions are my own. Read full disclosure here.
1. Adult Diapers - The hospital will provide you big mesh underwear and giant pads, but the bleeding will eventually go down and you'll want something more convenient to wear under your clothes for the ride home. I highly recommend getting Depends. You should only really need one pack as after a few days the bleeding will turn more into a period like flow and then you can switch to just using over night or heavy flow pads (My favorite is Always Infinity Extra Heavy Overnight).
2. Tucks Medicated Cooling Pads - The hospital provided me some, but you will definitely need or want more. I tried the Target brand, bad idea, they are not as good as Tucks! Tucks are more moist and soothing. The Target ones felt dry compared to the Tucks. This is a case where the price does matter, so spend the extra couple bucks and get Tucks!
3. Freezer Meals - I read that having meals pre-made was a big help to many parents after the birth of their baby, so I made it a goal to stock my deep freezer around 4 weeks before baby was due, and am so glad I did! There is no time to cook with a newborn and whatever time you do get is spent doing laundry, washing dishes, etc! It is so easy and convenient to pull out something from the freezer and throw it in the oven. If you are lazy or don't have time to make freezer meals before baby arrives, stock up on frozen food from the grocery store, like pizza or lasagna. Trust me, you will want quick easy meals!
4. Post Pregnancy Underwear - You may have heard of using a postpartum girdle to help with shaping your belly, but I much preferred the postpartum underwear! Your belly will be flabby after birth, kind of feels like jelly. I found wearing the underwear helped me look slimmer, back to my old self, and it was more convenient than messing with some girdle or belt. My favorite is this one, sold at Motherhood Maternity, unfortunately it was a clearance item when I got them, but it looks like it has been replaced with a solid one, which you can find here. I recommend getting two sizes, as after birth the larger size will be more comfortable, but once you start losing the weight, you'll want to go to your regular size again.
6. Pain Medication - Ibuprofen was a must have for me as I had a second degree tear. The hospital will provide it while you are there, but once you check out, you will have to get your own.
7. Stool Softener - This was only given to me once in the hospital, but my midwife said I could take Colace once a day once I got home. I found it was hard to make a bowel movement after giving birth, not so much painful, just for some reason I couldn't go for two days! Finally took some Colace and was able to go! Downside is it makes you super gassy.
8. Sweatpants, Leggings & Pajama Bottoms - After giving birth, these are the only types of pants you will want to wear. Jeans will not be comfy and you may not even fit into your old jeans yet. It can take a few weeks to a few months before you lose all that baby weight.
There are some other must-have items, but I didn't include them in this list as my hospital provided them. They gave me plenty of perennial ice packs (ended up with extra), a few heating packs (which I never used), a peri bottle, extra mesh underwear, and giant pads (ended up not using them all!). If your hospital doesn't provide these things or as much, you may want to stock up on your own. My nurse was awesome enough to give us a big bag of supplies to take home, so I didn't need to buy more.