Many moons ago, in fact exactly 2 months before Karalyn was born, I knit the Baby Albert Jacket for her. Almost 2 years later, Karalyn is still wearing the jacket. How did that happen? It was sized for a 12-month old. If you click on the link, you'll see the yarn particulars for this sweater - SWTC Bamboo. The yarn has grown. In fact, it has grown with Karalyn.
In the normal knitty scheme of things, a sweater that stretches out like this is baaaad, very baaaad. Serendipitously, though, for a toddler who needs to go shopping every 6 months for new clothes, this sweater is perfect! She's been able to wear it for 2 fall/winter seasons now and it just keeps on stretching.
I wonder if there's any way SWTC could market this wonderful feature. Superwash and super stretch! Grows with your child! A knitter's dream.