Kate Middleton's delicate pregnancy sparked rumors that she was carrying twins. Her frequent visits to the hospital, when she was pregnant for the first time with Prince George, apparently raised speculations that she could be giving birth to two babies.

The Duchess of Cambridge suffered from acute morning sickness, medically termed as hyperemesis gravidarum, during her pregnancy's first trimester in 2013. According to the experts, this condition is "more common" among women who are carrying twin babies so the public thought Kate Middleton will be giving birth to two heirs to the throne. 

Royal commentator Ingrid Seward recalled that there were discussions about this alleged twin birth during Kate's pregnancy. The royal expert received questions about the line of succession and said that whichever child appears first from the mother's womb will be considered the "firstborn" regardless of the baby's gender. 

Medical experts also said that hyperemesis gravidarum develops in women with a family history of the condition. If a mother has had it, then she will also experience this severe morning sickness for her future pregnancies.

Kate never mentioned if the women in her family suffered the same morning sickness. But, in February 2020, Kate opened up about her experience with this medical condition in the Happy Mum, Happy Baby podcast. She admitted that she was "not the happiest of pregnant people" and said she had hyperemesis gravidarum for all of her three babies -- George, Charlotte and Louis. 

The Duchess of Cambridge also shared that Prince William felt helpless about her condition. Kate said that her the first pregnancy trimester left her rotten and really sick. Since she couldn't eat well, she had to stay at a hospital to receive proper nutrition and hydration. Thankfully, her body was able to pull through after and still "grow new life." 

The hospital visits, however, prompted Kensington Palace to confirm the Duchess of Cambridge's first pregnancy earlier than planned. Apparently, the royal pair won't be able to hide Kate's condition any longer since she had to be in and out of the hospital.

Meanwhile, Kate's pregnancy has been the subject of online rumors after Princess Eugenie announced she and Jack Brooksbank will welcome their first baby in early 2021. Royal fans think Kate could also be heavy with her fourth child as she was spotted placing her hands on her stomach at a royal event in Kensington Palace. 

But, body language expert Judi James said it is likely "wishful thinking" from royal fans. She said that the royal's gestures and actions, while having a special guest at their home, was more like "fan awe" because her, idol David Attenborough, was that special guest.