Speculations about Kate Middleton's fourth pregnancy may be going on an overdrive. However, the Duchess of Cambridge herself may have recently given the one telling clue that she couldn't be carrying another baby. 

On a royal engagement to the National History Museum in London, Duchess Kate debuted the lightest hair color she has ever had. She Knows has the comparison photos of this new look to indicate that the Cambridge royal underwent a beauty makeover by having her hair highlighted a caramel honey-colored blonde shade.

Duchess Kate's beauty procedure raised a question about the safety of the hair dye's chemicals on her pregnancy, if she's indeed with child. Pregnancy website What to Expect recommends for moms to wait at least until the second trimester in getting the highlights because it's risky to take the chance of absorbing the chemicals when the organs of the fetus are developing?  Because of this, fans were disappointed to realize that Duchess Kate might not be pregnant with baby number four at all. 

Dr. Angela Lamb of the Westside Mount Sinai Dermatology Faculty Practice, however, said via Huffington Post that this is one of the misconceptions of hair dye chemicals and pregnancy. She said that the chemicals on the scalp don't stay too long to be absorbed in the bloodstream, which would cause harm to an unborn child. Dermatologist Dr. Jennifer McGregor, on the other hand, said that hair dye chemicals might only be harmful if the mom had an open wound, scrape or cut on the head that could raise the chances of absorption.

Talks that Duchess Kate is pregnant with her fourth child surfaced sometime over the summer when photos of her alleged baby bump surfaced online. U.K. bookers also received a surge of bets that Prince William's wife will give birth sometime in the first half of 2020, along with Meghan Markle, the Duchess of Sussex, and Princess Eugenie, Prince William's cousin, who are also both speculated to be in the family way. 

Meanwhile, royal observers have another speculation about why Duchess Kate isn't pregnant despite the buzz. She suffered from hyperemesis gravidarum or a severe form of nausea in her past three pregnancies, which required her to slow down and rest. Thus, she was not active and wasn't seen in public in the first trimesters of her pregnancy to Prince George, Princess Charlotte and Princess Louis.

However, Duchess Kate has an active royal schedule in recent weeks and she's even set to fly to Pakistan with Prince William for a visit. If she was pregnant, she would not be able to do this because she would be required to have a complete bed rest.