IMDB and Wikipedia both claim pneumonia as cause of death since that is what was reported in the New York Times obituary. A story in a 1930 edition of the Miami News does however reinforce the contention that it was death by childbirth.

Kay Laurell did not die from pneumonia. She died in childbirth.
Wikepedia is not correct. She had a son, don't know what happened to him, he was to inherit her estate. Read the newspaper article.

Couldn't resist. Click to enlarge.

The tableau described by gblawson is fairly standard French imagery; a depiction of Marianne (the symbol of France) fighting and victorious. This version of Marianne is inevitably depicted wearing a Phrygian cap (in Roman times indicating a freed slave) and one breast bared, recalling the goddess Athena. Probably the most famous depiction is Delacroix's 1830 painting "Liberty Leading the People."

Dancing figures on the beach,
As the marks left by their feet,
Are all long gone.
And rising in far off in the mist,
We behold the obelisk.

I don't know if they are "magnificent," but like they said on Seinfeld: "they're real, and they're spectacular!"

Is no reason to interrupt one's smoking.

As the war intensified, posing undressed began to be considered patriotic. If a woman stood naked posed as the Statue of Liberty, she was doing her duty for the American troops. Indeed, a record number of woman volunteered to be "undraped" in the 1917 edition's centerpiece. In the Ziegfeld Follies of 1918, which opened after the United States had joined the war, the curtain opened on a darkened stage to reveal a huge revolving globe with Kay Laurell perched on top, breast exposed. Little French girls in rags, a dying soldier attended by Red Cross volunteers, and a trench over which doughboys charged amid devastating gunfire completed the scene. Gazing down on a Ben Ali Haggin set piece designed to look like the world burning, Laurell was supposed to represent the spirit of France.

-- From "Striptease: The Untold History of the Girlie Show" by Rachel Schteir.

is nice touch on the beach.

My mother died in 1938 of pneumonia before antibiotics at the age of 36. A death like that now would be very unlikely.

This photo via the New York Public Library seems to be her famous costume from the 1918 Ziegfeld Follies. Some prude appears to have engineered a coverup. However those with a purely historic interest in Ms. Laurell's bosom may see it in several works by painter William Glackens, for whom Laurell repeatedly posed.

Perhaps the other lass is Eleanor Griffith, Kay's costar in the production of "Ladies Night" then playing at the Belasco. The Library of Congress archives contain one labeled photo of Miss Griffith: I think the smile is very similar.

Kay's friend on the right is the oar guitar girl from the canoe photo. Who was she?

So where's the shot of the reportedly magnificent breast? The February 1973 Playboy claims to feature Kay, among other Siegfeld [sic] Girls.

"Any woman could get money out of a man. What took real skill was getting the money and evading the sleeping." -- Kay Laurell

"She was the most successful practitioner of her trade
of her generation in New York. She had all the arts of a first-rate harlot. The skull and crossbones were there on the label for all to see." -- Helen Hayes

Another Broadway contribution to the war effort was the bust of Miss Kay Laurell. In the Ziegfeld Follies of 1917, a tableau by Ben Ali Hagan had Miss Laurell posed before crossed American and French flags in the fatigue uniform of a French soldier, blouse torn by some previously dispatched vicious German, exposing one reportedly magnificent breast. Word was that the French government ordered 200,000 copies of a photo of Miss Laurell's portrayal to use in an enlistment campaign. There is a suspicion that the word came from Ziegfeld's publicity people however.