Thor star Chris Hemsworth and his wife Elsa Pataky were stunned to learn the actress was expecting twins less than 18 months after their first daughter was born.

The couple welcomed baby India in May, 2012 and although the two stars were keen to extend their family, they were shocked to learn their brood is to triple in size within a matter of months.

Spanish actress Pataky tells British magazine Hello!, "We were in shock! On the one hand we were excited but we were also wondering, 'How are we going to cope?' We're a bit nervous but very happy and we think it's going to be fun and incredible, because relationships between twins are very special...

"Everything (is doubled), including the size of my belly! I look at it and go, 'I'm going to turn into a ball and bounce down the stairs!'... (But) I haven't wanted to know the sex of the twins in case I obsessed. With two, there's a bigger chance of a boy, so I hope so."