Princess Charlene is pregnant with twins: Who gets the crown?

Ever since Princess Charlene of Monaco confirmed that she is expecting twins, royal fans have been wondering about the rules of succession for multiple births. There can only be one reigning monarch — so who will inherit the throne?

If Charlene and Prince Albert welcome a boy and a girl, the boy will automatically be first in line – regardless of who is born first. This is called the “male-preference cognatic primogeniture,” which is still the law in Monaco, Spain and Thailand.

MORE CELEBRITY TWINS: CLICK ON THE IMAGE FOR THE GALLERYPrincess Charlene and Prince Albert are expecting twins

For centuries, giving male children precedence over female children was standard practice among European royals, but when Kate Middleton wed Prince William in 2011, the Commonwealth famously did away with the archaic succession law. Under the new amendment, the Duke and Duchess of Cambridge’s first-born child – boy or girl – would have inherited the throne.

Monaco's constitution, however, remains unchanged. If Charlene gives birth to twin girls, then the eldest will be first in line – that is, until Charlene becomes pregnant with a son, who would rule Monaco ahead of his older sisters.

The Commonwealth did away with male-preference inheritance in 2011

But what if the princess gives birth to twin boys? If Charlene has a traditional delivery without complications, the answer is clear: The first-born boy would be first in line for the throne.

However, if she requires a Caesarean-section – as is often the case with twins – then things become a bit more complicated. The first baby boy that the doctor lifts out will become the heir.

More: Princess Charlene's best maternity looks

Questions over Monaco's complicated rule of succession have come up in the past. Prince Albert, 56, has two acknowledged illegitimate children — daughter Jazmin Grace Grimaldi and Alexandre Coste — both of whom, because of their status at birth, are not eligible for the throne. Nonetheless, Jazmin and Alexandre stand to inherit a portion of his considerable wealth, which is estimated at around $1 billion.

According to Monegasque law, the crown can only be inherited by a child whose parents have been married at some point with the monarch's approval. Any children born out of adultery are also permanently excluded.

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