Prince Willaim and Kate Middleton
IN PHOTO: Britain's Prince William and his wife Catherine, Duchess of Cambridge sit on Centre Court at the Wimbledon Tennis Championships, in London Reuters

Kate Middleton is apparently still struggling with Hyperemesis Gravidarum, a pregnancy sickness characterised with extreme nausea and vomiting. Ever since her second pregnancy was announced last September 8, the Duchess of Cambridge has been out of the public eye. Kate is expected to meet with Singapore's president next week. However, according to a report she'll likely pull out again on the royal engagement due to her sickness.

Kate Middleton is scheduled for a brief meet-and-greet with Singapore's President on October 21. According to Daily Mail, the Duchess, along with husband Prince William, will formally welcome President Tony Tan on his U.K. visit that will last until October 24. However, few suspected that she may once again pull out of this royal engagement. The Daily Beast notes she may not be making any public appearances soon nor anytime ahead of the President's visit. The site credits a palace source who was quick to clarify that there's still no certainty whether she could commit to the duty. Kate reportedly "very much hopes" to be able attend. However, her presence at the engagement will depend on her health condition as the occasion draws near.

"As with all recent engagements her attendance will be reviewed closer to the time, depending on her health," the source said.

Palace officials previously told People that Kate Middleton's royal engagements are being reviewed daily. Likewise, her pregnancy is being monitored on a day-to-day basis. She reportedly already has engagements scheduled for October and November. However, it would seem that her health condition is of prior importance.

However, the Duchess' pregnancy sickness is supposedly getting worse. According to a previous report from the International Business Times, a family friend revealed that "she is not at all well." She's supposedly been vomiting a lot and she's been losing weight because of it. Furthermore, she's being looked after by not just one but two doctors. One of them is Alan Farthing, who has been likened to an "angel during the rougher moments" of Kate Middleton's pregnancy.

There's still no definite time as to when the Duchess of Cambridge will return to public appearances. She could supposedly be relieved of her pregnancy sickness when she's 16 weeks into her pregnancy. However, that would still be a long way to go since Kate Middleton is believed to still be ten weeks pregnant.