When knitting doll clothes from the bottom up, especially if using straight needles, the stitches at both edges of armholes tend to get stretched out of proportion.
This happens because the number of stitches being cast on for the yoke (or sleeves) almost always exceeds the number of underarm stitches that were bound off on the previous row. To accommodate the newly cast on stitches the armhole tries to expand itself and does that by making its edge stitches bigger.
Below is my technique of getting the armhole back to its needed size.
1. Use double yarn for armhole bind off.
Prepare 2 strands of the main yarn approx. 18” (45cm) each. On the bind-off row use the additional strand together with the main yarn to work the last stitch before the bind off and the bind off itself. The stitch created by the last bind off stitch becomes the first stitch at the other edge of the armhole. Drop the additional strand and continue working with main yarn only. Repeat doubling of yarn when binding off for the second armhole. Let the ends of the additional yarn to hang down on the wrong side of works until the bodice is finished.
2. Thread the tapestry needle using the yarn strand hanging from one of the edges of the armhole.
3. Insert needle into the top loop of the elongated stitch.
4. Turn the tip of the needle down and insert it through two horizontal loops below the elongated stitch .
5. Pull slightly on the yarn to close the gap.
6. Repeat steps 3-4-5 once more.
7. Weave in the yarn into knitted fabric using the invisible weave method. Clip off yarn.
8. The look of woven ends on the wrong side of fabric. They are almost invisible on the wrong side of work. . They will be completely invisible on the right side of work.
9.Do the same for both edges of each armhole. Finished armhole.