In the most public of ways, Marissa Mayer has just upended the longtime thinking on work and pregnancy.

Immediately after Yahoo announced that the Google executive would take over as CEO, Mayer announced she was pregnant.

Seven months along, said the 37-year-old, who was already shattering plenty of glass by taking the helm of a top technology company as a woman.

Marissa Mayer (Oliver Lang/AFP/Getty Images)

The baby, apparently a boy, is due in early October.

The response in the parenting world, especially among women has been explosive, with many flooding Twitter and other social networks.

“YAY @marissamayer Yahoo’s new CEO! She is also 7 mo pregnant- lets hope she inspires corps to create better options for all working moms,” tweeted Mia Farrow.

Another woman wrote: “... THIS is the modern woman. Pay attention America.”

#HavingItAll became a popular hashtag, an overt reference to the recent Atlantic piece, “Why Women Still Can’t Have It All,” by Anne-Marie Slaughter about how her experience as a State Department official was incompatible with family life.

Slaughter, for her part, tweeted: “Bottom line: We shd cheer 4 all women who make it to the top. But that’s not enough 4 real equality. Need better choices.”

In fact, Mayer told Fortune she doesn’t plan much of a maternity leave; she expects to be at home for a few weeks but work throughout.

That decision was met with less enthusiasm. As one tweet read: “Marissa Mayer: ‘My maternity leave will be a few weeks long and I’ll work throughout it.’ If that’s #havingitall, you can keep it.”

But before this milestone prompts the mythical Mommy Wars to bleed into maternity leave wars, the beauty of the Mayer news is that this real-life dilemma for many working women will be played out at the highest level.

Working Mother editorial director Jennifer Owens said it’s sure to trigger more discussion — which to my mind is always good — about how transparent professional women can be about pregnancies, the need for family leave and, of course, “the work-life integration discussion.”

“[H]ow a working mother chooses to balance work and family is her choice. Hers is an individual choice that won’t work for all new working moms, but works for her.

“We want all new working moms to have the support of their employers to create a paid maternity leave that works for their family and their company,” Owens said.

What do you think of the Mayer appointment and subsequent bombshell pregnancy news?

Related Coverage:

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Can dads have it all?

What ‘Having It All’ really means