My beautiful granddaughter was a micro-preemie, weighing less than a pound at birth. She still has some challenges but thankfully she is healthy, 15 pounds and almost 10 months old. One of her challenges is that she has nipple aversion, causing her to have to be fed through a gastrostomy tube (g-tube).
It's almost impossible to find just shirts for infants. The NICU nurses suggested modifying her onesies by sewing in a flap so the g-tube could be attached for feeding, without actually undoing the onesie. That would ruin a lot of onesies that probably wouldn't be used again with any future grandchildren so I decided on my own modification: converting a onesie to a shirt.
Very simple (and very cheap): Instead of buying new onesies, I just went to the thrift store, purchased the amount of onesies I wanted. They were 98 cents a piece. The "tools" I used were:
Marker (I used Crayola water-based because the markings come off in the wash)
Straight pins (ballpoint) for knit fabric.
Optional: needle and all-purpose thread
Sewing machine (use a ballpoint needle), but you don't absolutely need a sewing machine for this project.
Step 1: Marking, Pinning, and Cutting the Onesie
Lay out the onesie on a flat surface and use your hands to remove any bunched-up fabric. The shoulder seams should be even so that the onesie looks like it's hanging on a hanger.
Line up the ruler just a little bit above the leg openings as shown in the photo. Run a line on the bottom edge of the ruler. this is where you're going to cut the fabric.
Insert your pins horizontally through the two layers of the fabric and above the marked line. This will ensure the onesie doesn't shift during cutting.
NOTE: If you'd rather, you can always baste-stitch instead of using the pins.
When you're done cutting, remove the pins.
NOTE: I suppose if you wanted to make little panties instead of a shirt, you could mark high enough on the onesie to allow you enough room to insert some elastic. Hmmm...if I can't find shorts, maybe I'll do that project too.
Step 2: Pinning the "shirt" in Preparation for Sewing
Turn the onesie inside out. Fold the bottom edge of the shirt up a 1/2 inch and pin vertically all the way around. Start at or near the side seam. I pinned directly on both sides of the side seam because it can be so bulky at that location.
NOTE: Again, if you'd prefer, you can always baste stitch instead of pinning.
It doesn't have to be absolutely precise. Remember, babies grow so fast that a shirt will quickly become a mid-drift. Besides, these are thrift-store finds.
Step 3: Preparing the Sewing Machine
Above is a picture of the settings I used on my sewing machine. These settings were used in order to help in the fabric not puckering:
Low tension (mine is at 1)
Long stitch (mine is set at 3)
Zig zag stitch (mid-range to long)
It's a good idea to experiment with maybe the leftover fabric to see what works better for you.
The needle position is also set in the middle. This has nothing to do with keeping the fabric from puckering, just where the needle will sew through the fabric. A different setting may be better for you.
When feeding the fabric under the presser foot, do not pull on the fabric from behind. Since this is knit fabric, it will only stretch it out and may cause a bad result. Just gently guide the fabric under the presser foot.
NOTE: If you don't have a sewing machine, you can always just hand sew it.
Step 4: Sewing the Shirt
The fabric edge is sitting right under the right edge of the presser foot. Start at or near the seam, making sure to anchor your first stitches. Also, anchor your ending stitches.