The leader of political party Podemos, Pablo Iglesias, and his partner, Irene Montero, also a top party member, have become the parents of twin boys.
The babies, which are expected to be called Leo and Manuel, were born three months prematurely and will stay in hospital for the next two months.
Speaking after his partner gave birth after only six months, Iglesias said, " They've been born much earlier than expected. We hope all goes well. They are in the best hands."
The high-profile couple were at the centre of a controversy in May when it emerged that they had bought a 600,000-euro house outside Madrid to bring up the children in. Their party, Podemos, was founded as part of an anti-capitalist street movement and they were seen as potentially abandoning their political roots. An overwhelming majority of party members then backed them in a subsequent online vote.