NICE, France — Brad Pitt was emotional but calm, Angelina Jolie laughed and chatted. The world’s most famous celebrity couple were joined in emotion during the birth of their twins — a boy and a girl — and all “are doing marvelously well,” the doctor who delivered the babies in a seaside hospital on the French Riviera said Sunday.

The newborns — Knox Leon and Vivienne Marcheline, born one minute apart Satuwrday evening — are the ultimate million-dollar babies, with experts estimating their first photos will fetch a fortune.

For now, mother, father and newborns are resting out of the public eye on the fifth floor of the Lenval hospital, behind blue mirrored windows that provide sweeping views of Nice’s sun-drenched beaches, but are specially treated to deflect the prying lenses of paparazzi.

Jolie’s obstetrician, Dr. Michel Sussmann, said the 44-year-old Pitt was at Jolie’s side during the delivery, looking on as the doctor performed a Caesarean section to deliver Knox, weighing in at slightly over 5 pounds, and Vivienne, who weighed 5 pounds.

“He was my assistant,” Sussmann joked.

He said Jolie, 33, is expected to stay in the hospital for a few more days and that she now needs rest. The four other Jolie-Pitt children — Maddox, 6; Pax, 4; Zahara, 3; and Shiloh, 2 — have not yet seen their new sister and brother, he said.