How Will Prince George Adapt to a Little Sibling?
09/08/2014 AT 07:45 AM EDT
With Prince William and Kate's baby, whose impending arrival was announced Monday, likely to be born in the spring, Royal Child No. 2 will be about 21 months younger than brother George.
Perhaps fittingly, that is nearly the same age difference between both William and Kate and their respective siblings.
The difference between Kate and Pippa Middleton – who last week turned 31 – is 19 months, while friends have told PEOPLE that William enjoys the nearly 27-month difference that exists between him and Prince Harry.
This may explain the timing of William and Kate's second child.
(One thing certain is that only child George had better get used to having a sibling – and maybe even sharing his toys. At a public playdate in New Zealand in April, feisty George memorably grabbed playthings away from other children.)
Looking at sibling relations and how the age difference might be a factor, Jane Munro, a midwife at the Royal College of Midwives, tells PEOPLE that the average age gap between siblings in the U.K. "is about two years and nine months. That fits in with what some of the psychologists suggest, too."
Then again, she notes, "When you're ready, it's the right time. But there are things to think of, like sleeping through the night, having two babies in nappies, et cetera."
Physically, to insure that a mother's body has recuperated from the previous pregnancy, Munro says, "Research suggests that waiting between 18 to 23 months before thinking about conceiving is good in terms of the woman's body having recovered, because [a pregnancy] is quite traumatic. It's very hard on the body."
Additional reporting by STEPHEN M. SILVERMAN