Kate Middleton & Princess Charlotte
Princess Charlotte's children will not inherit her royal title. Pictured: Kate Middleton and Princess Charlotte leave from Victoria Harbour to board a sea-plane on the final day of their Royal Tour of Canada on Oct. 1, 2016 in Victoria, Canada. Getty Images/Stephen Lock

Princess Charlotte's future children will not be called prince or princess.

Most might assume that when one is born from a royal family, every lineage will be called prince or princess. But that is not the case, especially for Kate Middleton and Prince William's future grandchildren with daughter, Princess Charlotte.

"Royal titles are inherited through sons, so if Princess Charlotte has children they would not automatically inherit the titles 'HRH,' 'Prince,' or 'Princess,'" said Lucy Hume, associate director of Debrett's, a trusted resource when it comes to British peerage, Good Housekeeping reported. The publication noted that this is the reason why Prince Andrew's daughters Beatrice and Eugenie are called princesses, but Princess Anne's daughter Zara Phillips does not have any royal title.

In general, there are only two ways for one to become a princess: either she is a daughter of a prince (British sovereign) or has to marry one. The second option applies to Middleton. She took the title Princess William of Wales after marrying the Duke of Cambridge. She is also called Her Royal Highness, Duchess of Cambridge.

In related news, the gender of Middleton's third baby has not been confirmed yet, but there are already reports suggesting that Prince Harry will not be among the child's godparents. "It is possible Beatrice or Eugenie might be a godparent to the new baby," Richard Fitzwilliams told Express. In addition to the two Princesses of York, the Duke and Duchess of Cambridge are more likely to choose from their close friends.

As for Middleton's pregnancy, she is already in a much better condition after suffering from hyperemesis gravidarum or severe morning sickness. In fact, Middleton's family is convinced that the worse of her condition is already behind them. "She has such a rotten time during this early month," a source told E! News. "But she's out of the woods now and doing well."

On Tuesday, Middleton is set to host a reception at Kensington Palace for World Mental Health Day. The gathering is a celebration for the contribution of those working in the mental health sector across the UK. Prince William and Prince Harry will join Middleton at the event. The three are active advocates of mental health.