Many are rooting for Prince William and Kate Middleton to have another baby.

A few weeks back, Prince Harry and Meghan Markle announced that they are expecting their first child. This prompted some royal fans to speculate that the Duke and Duchess of Cambridge will have another addition to their brood, too. Bookmakers Ladbrokes have put the odds of Prince William and Middleton announcing their fourth child at the end of 2019 at 4/1.

"Baby fever is in full swing in the Royal family right now so it's no surprise to see odds on a fourth Will and Kate baby so short," Ladbrokes spokesman Alex Apati said (as quoted by Express).

After welcoming their youngest son, Prince Louis, there were already bets suggesting that the little prince won't be the couple's last bundle of joy.

"We have already taken bets on Kate and William having a fourth baby and the odds suggest Prince Louis won't be their last," John Hill of Coral said. "Prince Louis is fifth in line to the throne, therefore he is a big price to ever become King."

Princess Diana's former royal butler, Paul Burrell, also believed that Prince William and Middleton would have four kids.

"I bet William will have four," Burrell said. "Both William and Harry wanted more brothers and sisters when they were young but it wasn’t to be."

Meanwhile, the Duke of Cambridge's friends reportedly told Richard Kay that he wanted to follow in the footsteps of the monarch and have four children, too.

"He would love to emulate his grandmother and have four children and he would be very happy if it was another girl," the source said. "Having Charlotte was an improving effect on George who was a bit of a tearaway in the early days, so he knows the benefit a second daughter might bring."

However, some sources also believed that the couple might not consider another baby because Middleton had struggled with severe morning sickness in her first three pregnancies.

"I can't imagine Kate will want any more given the ordeal that she goes through every pregnancy. I should think that three children is enough," an insider told People in 2017.

Prince William and Kate Middleton
Kate Middleton and Prince William will have another royal baby, betting odds suggest. Pictured: Prince William and Middleton react as they paint a part of a painting with Columbian artist Dairo Vargas, during the first Global Ministerial Mental Health Summit, co-hosted by the UK Government and the OECD, in London on Oct. 9, 2018. Getty Images/Eddie Mulholland