She finally met her new nephew, Archie, and now, sources say that Kate Middleton could have baby fever and is getting ready to have a fourth baby with Prince William.

According to New Idea magazine, because the Duchess of Cambridge has seen the bond between her two eldest children, and would love to give her youngest, Prince Louis, another sibling close in age to bond with in a similar way as well.

“Kate has seen the bond between George and Charlotte and thinks it would be lovely if Louis had a sister closer to his age,” a source told the magazine.

In addition, if she expresses a desire for a fourth child, the source maintains that Prince William would oblige since he always wants to make his wife happy.

“Kate is doing things her way but William has always supported her and will do anything to make her happy; that is a promise he made before they married,” the source added.

This comes not long after another report claimed that Middleton was eager to have another child, even though she has suffered from hyperemesis gravidarum during her past three pregnancies.

“Catherine would like another baby,” sources said at the time. “She loves children and is prepared to put herself through another pregnancy even though they have been complicated by severe morning sickness in the past.”

However, even if Middleton does want a fourth child, it still may be a little while before she could announce a pregnancy—and it may not happen until 2020.

As it turns out, the World Health Organization recommends that women often wait 24 months to conceive after another pregnancy, though the gap could be shortened to 18 months. If Middleton, who is 37, were to wait until she was 18 months past her pregnancy with Louis, the earliest she could conceive would be in October. If she was able to wait the recommended 12-week period to announce her pregnancy (something she has not been able to do in the past because of the condition she’s suffered from), then she would be announcing her next pregnancy until early 2020.