Is the show over for Beyoncé?

'I feel like 30 is the ideal age," Beyoncé Knowles said, when asked when she might have children, "because you're mature enough to know who you are and have your boundaries and your standards, and not be afraid or too polite, but young enough to be a young woman. I'm so looking forward to it."

Knowles, the R'n'B phenomenon who has won 16 Grammy awards, sold more than 75 million records, is in the trinity of female artists dominating the music industry (alongside Lady Gaga and Adele), and has become part of Barack Obama's entourage, sprung the news on her fans just a week before her 30th birthday.

She announced on Sunday night that she and her husband, the rapper Jay-Z, were expecting their first child. As she strolled up the red carpet at the MTV Video Music Awards in Los Angeles, clutching at a growing bump barely concealed beneath a red silk ballgown, she told the assembled paparazzi: "I have a surprise!"

The revelation could interfere with plans made by Beyoncé's US record label, Columbia/Epic. In a June interview with the music magazine Billboard, Columbia/Epic's chairman Rob Stringer said the touring plan for Beyoncé's latest album, 4, was "extensive", with commitments pencilled in for the next 18 months.

"She is well versed in being a global artist," said Mr Stringer. "The touring plan is extensive. The promo plan is extensive. We also know we are going to put out a lot of singles and ... shoot a lot of videos from the record."

The record label was not returning calls last night, but industry insiders speculated that the pregnancy would see Beyoncé step out of the limelight for at least 18 months to two years.

While disappointing to those fans who were hoping to see her perform live, her decision to curtail her work commitments and start a family will only endear her to an audience who lap up her message of female empowerment – albeit one delivered with support from scantily-clad backing dancers, who somewhat prematurely celebrate the victory of women against patriarchal forces.

Beyoncé's barnstorming appearance at the Glastonbury festival in June (the first woman to headline there in 20 years) was characterised by her customary gusto and glamour, and saw a largely female crowd singing along – from "All the women who are independent throw your hands up at me", to "Who runs the world? Girls!" – and trying to copy her moves. She is one of few artists who could turn up on the main stage dressed in a gold glitter jacket and pants and still pull off the look.

Beyoncé's earnings potential has never been higher, but she seems determined to turn now to family matters, declaring in an interview earlier this month that she wanted to "focus on her marriage" and be "the mother I want to be".

News of her pregnancy will reinforce her image as someone who is "serious and responsible", according to Jessica Coen, editor-in-chief of the women's website Jezebel.com. "Beyoncé is incredibly successful and financially independent without her husband. People love them both, but at 30, as a career woman, she has achieved much more than many women ever will. She is attempting to have it all. No one, on the face of it, you would think, can have it all. But she's making a grab for it."

Coen added: "I don't think you will ever see her become a stay-at-home mum. She's been a performer since she was a teenager. I can't see her stopping that."

Peter Robinson, editor of the pop website Popjustice.com, said he hoped the former Destiny's Child singer would return to making music after her pregnancy. "Her performances are still incredible and it is clear she is still enjoying it," he added. "I don't know why she would want to pack it in. I don't think she would need to, really. She's not like Lady Gaga, who appears to be doing something every week. She has a lot of down-time."

Alex Miller, the executive editor of Vice magazine, added: "It's not like the press is going to leave her alone when she's having a baby. It won't damage her image. And even if it does I'm sure Jay-Z can pull out another collaboration with Kanye [West] and buy them another island."

WHEN STARS BECOME MUMS

Elizabeth Hurley As Hugh Grant’s partner, she made headlines with “that dress” at a film premiere in 1994, then enjoyed several years of advertising campaigns and film roles. After her first child in 2002 her movie career bombed and she became best known, once again, for her romantic relationships.

Paula Radcliffe After a four-year period in which she won six major marathons, she gave birth to a daughter in 2007 at the age of 33. She won the New York marathon in 2007 and 2008, but has not seriously challenged for other major honours since.

Ms Dynamite Niomi McLean-Daley, aka Ms Dynamite, released her debut solo album in 2002 and was awarded the Mercury Music Prize three months later. The following year, just before a tour of Europe, she became pregnant and put her career on hold. After returning to the limelight she has struggled to match early success.