Kate Middleton Carrying Twins?

When Prince William and Kate's official announcement that she is pregnant came Monday, the palace said she was "expecting a baby."

But in light of the fact that the Duchess of Cambridge is also suffering from hyperemesis gravidarum, a form of acute morning sickness, there has been growing speculation that she may, in fact, be expecting twins.

According to the National Institutes of Health, the Duchess's rare condition tends to appear more often in women carrying twins.

So what would it mean for the royal family if Kate, 30 – who was discharged from the hospital Thursday – were to deliver two little royals? A pair of heirs?

Nope, royal experts tell PEOPLE. In fact, it's all a bit complicated.

The firstborn twin would have a completely different path than his or her sibling, says royal historian Robert Lacey, author of The Queen: A Life in Brief: "The first child to appear will have precedence. Whichever one comes out first will be the heir – and it will be the call of the obstetrician if there is a caesarean section."

And the obstetrician will make that delivery based on the location of the babies during labor, Mark Johnson, Professor of Obstetrics at Chelsea and Westminster Hospital, tells PEOPLE.

cutCollapse )