The British Prime Minister Boris Johnson's fiancée Carrie Symonds flaunted her baby bump first time since her pregnancy announcement. 10 Downing Street released photographs of her showing off her baby bump.

The 31-year-old was photographed alongside the prime minister at a reception held at Number 10 on Thursday to celebrate International Women's Day. "Tomorrow it's #InternationalWomensDay. We celebrated earlier this week by hosting a reception at Downing Street," reads a tweet by 10 Number.

The pictures were released on Saturday and gave a glimpse of Symonds' growing baby bump, The Telegraph reports. A huge rock also made itself visible in the picture. It is the engagement ring that Boris Johnson has given his fiancée.

According to Vogue UK, The sparkler has an oval-cut emerald surrounded by diamonds in a pavé band. The striking design is a complete departure from a traditional diamond solitaire. Symonds was glowing in a high-neck floral print Anthropologie dress for the occasion.

Johnson and Symonds announced last weekend that they were engaged and expecting a baby in the "early summer." Symonds told her followers on social media that she felt "incredibly blessed." She added that she and Johnson, 55, got engaged at the end of last year and "we've got a baby hatching early summer."

Symonds had not been seen in public since the general election in December. Besides, the prime minister said he will almost certainly take paternity leave when his new child is born later this year.

At the reception to mark International Women's Day, Johnson said there remains "so much more to do" to ensure equality between men and women. He was addressing a gathering of schoolgirls inside Number 10. He told how he had learnt that sexism is "complete rubbish" at an early age.

Olympic gold medallist Dame Kelly Holmes and mathematician Anne-Marie Imafidon were also speakers at the event. "I'm left miles and miles behind and yet historically men have enjoyed this kind of automatic assumption that they are going to be of a certain position in life - and that still needs to be challenged," Johnson said.

Boris Johnson and Carrie Symonds
The British leader, who took office last summer and then swept to an emphatic victory in the country's December general election, will be the first UK prime minister to wed while in office for 250 years. Photo: AFP / Oli SCARFF

Johnson has four grown-up children with his second wife Marina Wheeler. He has already reached a financial settlement with her recently over their divorce.