Pink

I don't have source for this artifact. 

However, the video below shows another textile and offers a source. 

The Josef Kohout/Wilhelm Kroepfl Collection 

United States Holocaust Memorial

You Tube

1920, Paper Doll Baby Bobby.

Winterthur Museum and Library

The march toward gender-specific clothes was neither linear nor rapid. Pink and blue arrived, along with other pastels, as colors for babies in the mid-19th century, yet the two colors were not promoted as gender signifiers until just before World War I—and even then, it took time for popular culture to sort things out.In 1927, Time magazine printed a chart showing sex-appropriate colors for girls and boys according to leading U.S. stores. In Boston, Filene’s told parents to dress boys in pink. So did Best & Co. in New York City, Halle’s in Cleveland and Marshall Field in Chicago.

Today’s color dictate wasn’t established until the 1940s, as a result of Americans’ preferences as interpreted by manufacturers and retailers. “It could have gone the other way,” Paoletti says.

So the baby boomers were raised in gender-specific clothing. Boys dressed like their fathers, girls like their mothers. Girls had to wear dresses to school, though unadorned styles and tomboy play clothes were acceptable. 

Above text source smithsonianmag.com. Go to link to read full article.