Helen Gurley Brown, a journalistic pioneer who helped shape the self-image of American women through her work as editor of Cosmopolitan for more than three decades and as author of influential 1962 bestseller “Sex and the Single Girl,” died in New York on Monday after a brief hospitalization. She was 90.

Gurley Brown wrote “Sex and the Single Girl” at the suggestion of her husband, film producer David Brown, who died in 2010 at age 93 (he produced movies included “Jaws,” “The Sting” and “The Verdict”).

Brown thought she write a book about a young single woman should go about having a love affair. The then-shocking work, which remained on the bestseller lists for more than a year and was published in 28 countries, ignited her career.

“Sex and the Single Girl” was adapted into a 1964 film starring Natalie Wood, Tony Curtis, Henry Fonda and Lauren Bacall.

When asked in 2006 about “Sex and the Single Girl,” Gurley Brown explained, “Before I wrote my book, the thought was that sex was for men, and women only caved in to please men. But I wrote what I knew to be true — that sex is pleasurable for both women and men.”

The book also encouraged young women to find fulfillment in work.

In 1965 Hearst Magazines, interested in her pitch for a magazine targeted at single women, hired Gurley Brown to turn around its languishing title Cosmopolitan, which became her bully pulpit for the next 32 years.

Gurley Brown’s “formula for honest and straightforward advice about relationships, career and beauty revolutionized the magazine industry,” said Frank A. Bennack Jr., CEO of Hearst Corp. “She lived every day of her life to the fullest and will always be remembered as the quintessential ‘Cosmo girl.’ She will be greatly missed.”

As editor-in-chief, Gurley Brown grew Cosmopolitan’s sales and advertising. It is the top-selling young women’s magazine in the world, with 64 international editions. In 1997, Gurley Brown left the flagship magazine to be editor-in-chief of Cosmopolitan’s growing international editions.

Gurley Brown also continued writing books, including “Sex and the Office” (1965), “The Single Girl’s Cookbook” (1969) and “Sex and the New Single Girl (1971), an updated version of her first book.”

Gurley Brown was eagerly sought for appearances on television talkshows, where she eagerly commented on sexual mores and the culture at large, guesting on “The Tonight Show With Johnny Carson” at least 18 times between 1971 and 1983 and even appearing on “The Howard Stern Show” in 1991. In the 1980s, she had a weekly spot on Good Morning America and briefly hosted her own show, “A View From Cosmo,” on Lifetime.

She also appeared as an interviewee in documentaries such as “Inside Deep Throat,” Lew Wasserman doc “The Last Mogul” and VH1’s “Sex: The Revolution.”

Gurley Brown was in Green Forest, Ark. The family moved to Los Angeles in the late 1930s. Gurley Brown graduated from high school as class valedictorian, spent a year at the Texas State College for Women and returned home to put herself through Woodbury Business College.

After a long series of secretarial jobs, she began work as a copy writer at advertising Foote, Cone, and Belding. By the late 1950s, she had become the highest-paid female copywriter on the West Coast.

In 1959, Gurley Brown married Brown, then a film executive at 20th Century Fox and later an independent producer. During their marriage, Brown was a partner behind many of Gurley Brown’s projects, even writing Cosmo cover lines.

Gurley Brown was named one of the 25 most influential women in the U.S. five times by the World Almanac, and she was inducted into the Publisher’s Hall of Fame in 1988. The Magazine Publishers of America honored her with the 1995 Henry Johnson Fisher Award, the magazine publishing industry’s highest honor. Gurley Brown was the first woman recipient.

In 1986, the Hearst Corp. established a chair at Northwestern U.’s Medill School of Journalism in her name, the Helen Gurley Brown Research Professorship.

Her memoir “I’m Wild Again: Snippets From My Life and a Few Brazen Thoughts,” was published in 2000. A biography of Gurley Brown, Jennifer Scanlon’s “Bad Girls Go Everywhere: The Life of Helen Gurley Brown,” was published in 2009.

In January, Gurley Brown gave $30 million to Columbia and Stanford Universities. The gift created the David and Helen Gurley Brown Institute for Media Innovation, housed at both Columbia’s Graduate School of Journalism and the School of Engineering at Stanford. The center represents the “increasingly important connection between journalism and technology, bringing the best from the East and West Coasts,” both schools announced. The journalism school said its $18 million share was the largest donation in its 100-year history.

Donations may be made to the Pussycat Foundation, c/o Karen Sanborn, Hearst Corp., 300 W. 57th Street, New York, NY 10019, to fund media innovation at Columbia and Stanford.

A fall memorial will be announced at a later date.