Kate Middleton has sparked third baby pregnancy rumours yet again. It's just been four months since the birth of Princess Charlotte and the Duchess of Cambridge is reportedly already in the early stages of pregnancy with baby number three. 

According to recent reports, the Duke and Duchess of Cambridge are all set to become parents soon again, as Kate is due to deliver third child with Prince William sometime late April or early May, reported Hollywood Life (via Star Magazine).

"She's in the early stages of pregnancy with baby number 3. She's not taking any chances," an alleged source told the magazine.

The mother-of-two has been in the news for the past few months and has drawn a lot of criticism for her lack of visibility and no-show at high-profile social and royal events, including the much-talked about wedding of socialite Daisy Dickson and estate agent Bear Maclean.

The Duchess was scheduled to join Prince William at All Saints Church in Thurlestone, South Devon, for the wedding of the Duke's old friend Maclean. But, she couldn't make it to the event and instead, William showed up at the event with sister-in-law, Pippa Middleton.

"William put his foot down and decided her heath must not be put at risk. So Kate rested at home and spent her day relaxing and playing with George and Charlotte," the source said.

Apparently, even the Queen has been very supportive of Kate's situation, the report further stated. "Kate has the Queen's blessing to forgo royal duties for at least two months, until she overcomes the threat of sickness," the source said.

In fact, the report has also claimed that the third royal baby is due in late April. "Kate's third baby is apparently due in late April or early May, so she'll likely be showing by the New Year. She knows the paparazzi will try everything to get the first photos of her bulging swimsuit — that's why she wanted to take an earlier vacation. She figures her bump won't be prominent in November, so she can relax in her bikini without her pregnancy being so obvious," the source said.

Various tabloids have been trying to reason out her absence, isolation and morning sickness with various speculations. While all this do point at a possible pregnancy, many still maintain that Prince George and Princess Charlotte's mother is suffering from postpartum depression.

But Celeb Dirty Laundry has claimed that the isolation is not due to morning sickness or pregnancy, but because she is insecure about Prince William and issues in her marriage.

The report said that Kate is aware that her marriage is going through a rocky phase and having a third baby isn't a wise decision right now. Apparently, pregnancy will only complicate things between William and Kate and that the Duke may end up cheating on the Duchess, the report claimed further.

Now, only time will tell if this third baby pregnancy rumour is true or not, or whether Kate Middleton is worried about Prince William and her marriage.