This instructable will show you how I converted a regular king size pillow into a maternity pillow to support my belly and back, and keep me from rolling onto my back in the middle of the night.

Any regular king size pillow case should still fit over this.

This pillow is more for stomach support and preventing rolling than for back pain. If you have back pain, this pillow may or may not help. If your back pain is related to the weight of your stomach pulling sideways at night, this pillow might offer some relief. If it's related to hip pain, this probably won't help much. However, you can also sleep with a regular pillow (or a specialty pillow) between your knees, which can provide a lot of relief for lower back pain. I like the combination of a knee pillow and a pillow like this one, because I can still easily change from one side to the other at night, but can't roll flat on my back in my sleep. Most of the large maternity body pillows on the market, which provide knee support as well as tummy/back support, are a) quite expensive, and b) very bulky.

Stomach sleepers may also be able to use a pillow like this to be able to sleep on their stomachs for a little longer. I'm just at the point where laying on my stomach isn't normally comfortable, but I can lay on this on my stomach and it supports my sides enough that there's no pressure on my baby bump.

You will need :

~ 1 king size pillow ("firm" is best)
~ a seam ripper (or a small, pointy, sharp scissors)
~ a pencil (or fabric pencil/marker)
~ something to use as a straight edge
~ straight pins
~ cotton thread
~ sewing needle or sewing machine

I used a brand new (but cheap) "firm" pillow for this project. If you have an old pillow lying around that would probably work fine, but if it's really old and lumpy the end product might not be very comfortable!

Step 1: Measure

Measure how large you want the gap in your pillow to be.

I did this by lying in bed and placing a regular pillow in front and behind myself. Once I had them in a comfortable position, I carefully got up and measured the distance between them.

I highly suggest you measure, or at least do this step and guesstimate the distance. I ended up with a middle measurement of 7 inches, which was much smaller than I would have thought!

Step 2: Rip the Seam and Gut the Pillow

Use your seam ripper to begin opening up the seam on one of the long sides of the pillow.

Begin in the middle, approximately where the flat section will be on the end product, and open a hole big enough to comfortably get your hands inside. Reach in and separate the stuffing into two halves, pushing it over to roughly where it will be in the finished pillow.

Finish opening up the entire seam along the long side, and remove the two pieces of stuffing.

*You could probably just open the entire seam, remove the stuffing as one piece, and cut it in half. I did it the way I outlined above because:
a) I had hopes of being able to just open up the middle of the seam, then pin and sew with the stuffing inside. I quickly realized that wasn't going to work!
b) Pushing the stuffing to approximately the right size with the rest of the seam still there to keep the stuffing in place may make re-stuffing later a little bit easier.

My goal here was to keep the stuffing as intact as possible, to prevent lumps and unevenness at the end.

Also, if your pillow has trim like mine did, and you want to reattach it, now would be a good time to pin it back on to one side of the pillow skin and sew it in place. I didn't think of this until later, and this step would save you the hassle of trying to pin and sew three layers together all at once while under the pressure of the stuffing. Honestly, I'd suggest just cutting the trim off this side, and sewing the corners of the pillow down well at the cuts (no one's going to see it, and ideally you should put the whole thing in a king size pillowcase while it's in use anyway!)

Step 3: Mark and Pin

Measure your pillow "skin" and determine the center. In my case, my pillow was 35", so my 7" flat portion fell between 14" and 21"

Use your pencil and a straight edge of some kind to mark a line on either side of the flat portion of your pillow. Pin the two halves of your "skin" together along the lines.

Step 4: Follow the Lines

Sew along the two lines. I chose to use a triple stitch for strength - possibly overkill, but since I was sewing on the machine, why not?

If you haven't reattached the trim yet (and you plan to), leave a gap at the end of your seam instead of sewing right to the end.

If you're removing the trim, or you've already re-sewn the trim to one side, you can sew right to the end, just make sure to fold the edges of the pillow"skin" back together properly (unfinished edges folded in).

*If you want to wash your pillow"skin" to remove your pencil lines, now's the time to do it (assuming you've either removed the trim, or re-sewn it to one side)

Step 5: Stuff Your Pillow

Re-stuff your pillow. If you're picky (like I am!), you might want to reverse your stuffing (so the side you pulled apart is towards the outside edge of the pillow).

I found it easiest to gather one end of the stuffing in one hand and push it in as far as possible. Once it was started it was fairly easy to push the rest of the stuffing into place without deforming it.

Step 6: Pin and Sew

Pin the long side back together, making sure to fold the unfinished edges of the pillow"skin" back in as you pin.

If you didn't cut off or sew the trim back on one side already, I suggest first pinning the trim to one side, then pinning the other side to the trim and the first side (make sure to get all three layers with the new pins). The tension from the stuffing makes it really difficult to just pin all three layers together at once.

Sew the seam back together. This might be easier to hand sew, though I used my machine. If you're using a machine and you're brave enough, I suggest sewing over the pins and removing them afterwards. The tension created by the stuffing tends to push the layers out of alignment as you remove the pins, otherwise (might not be a problem if you're not trying to sew the trim back in at the same time!)

Step 7: All Done!

All done! The end result is a very firm pillow with a gap just big enough for you to lay in the middle. The pillows might seem a little firmer than necessary at first, but remember, they will compress with use!