Kate Middleton announced she was pregnant with baby No. 2 on September 8, almost five weeks ago. Since then, Kate Middleton has stayed out of the public eye due to her acute  hyperemesis gravidarum, or morning sickness. Will we see her baby bump at her first royal engagement since her announcement, on October 21? If we do, it may hint that Kate Middleton is having twins!

According to E! News, Kensington Palace confirmed Friday that Kate and husband Prince William are scheduled to welcome the President of Singapore, Tony Tam, on behalf of Queen Elizabeth II at the Royal Garden Hotel on October 21 - this will be the Duchess of Cambridge's first public appearance since she announced she was pregnant with baby No. 2.

Express reports that Kate is believed to be around 11 weeks pregnant. According to BabyCenter.com, baby bumps typically form between 12 and 16 weeks. The website also reports that "twins or multiples are responsible for an early bulge."

So if Kate Middleton starts to show a baby bump on the 21st, her early signs of pregnancy would suggest she could be carrying twins!

Two years ago when Kate was pregnant with Prince George, she was back on duty after only two weeks. So far, the Duchess of Cambridge has missed "16 engagements on six different days, including 10 planned for a two-day trip to Malta that her husband undertook instead while she stayed at home," Express writes.

In a public apology letter, the pregnant duchess wrote, "I am truly sorry that I cannot be with you all today as you celebrate this milestone. As patron of The Art Room, I feel great pride to see the work that the charity is doing. Vulnerable children flourish in the safe havens that The Art Room provides; this highlights just how important it is to support children at a time when they most need help and support."

What do you think? Is Kate Middleton and Prince William expecting twins? Or is this just an extra-tough pregnancy for Prince George's mom? Let us know in the comments section below!