Pregnant Kate Middleton Won't Reveal the Sex of Her Second Baby Just Yet

Kate Middleton and Prince William are keeping the cards close to their chest right now when it comes to their future arrival.

The duchess--who is only 13 weeks pregnant--may have made several public appearances over the last few days, but she's staying mum about any details regarding the sex of her second child.

The expectant royal attended a dinner last night in honor of one of her charities, Action on Addiction, and showed off her tiny baby bump in a stunning black Temperley London gown.

She told supporter Christopher Holder that she "loved" being out on the town after spending several weeks at home where she's been resting due to hyperemesis gravidarum.

Holder told reporters, "There was talk about the baby, and I thinks someone asked the question, 'What is it going to be?' but she didn't answer."

He added, "We're obviously all aware, there was a bit of nervousness that this may not happen with her being here. But we're so pleased that she's recovered and she's here. What she's done for Action on Addiction is superb in terms of putting it on the map."

On Tuesday, Middleton made her first public appearance since announcing that Prince George is due to become a big brother on Sept. 8.

The brunette beauty accompanied William to greet and welcome Tony Tan, the President of Singapore, and his wife, Mary, to the U.K.

Later that same day, she stunned in a baby blue Jenny Packham wrap dress when she attended the 2014 Wildlife Photograph Awards at the Natural History Museum in London.

Meanwhile, the Palace announced earlier this week that Kate and William's baby is due in April.