Matthew McConaughey's girlfriend gave birth to a baby boy on Monday night, the actor told OK! magazine.

The baby was born at 6:22 p.m. PT in Los Angeles and weighed in at 7 pounds, 4 ounces. The infant is the first child for McConaughey, 38, and Camila Alves, 24, his girlfriend of two years.

"A healthy baby boy was born," McConaughey told OK! magazine. "Camila and I were side by side the entire time. We are both tired and elated, and are so happy to have created the greatest miracle in the world — Having a child and making a family. Now comes the greatest adventure — raising one, together."

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In January, McConaughey announced the couple were expecting on his Web site.

"Camila and I made a baby together...," he wrote at the time. "We are stoked and wowed."

McConaughey's oldest brother, Rooster, told People that having a nephew is "going to be fun."

"He'll make a really good dad because he's got a lot of patience. I'm excited for him. It's about time," Rooster said.

Alves, a model and handbag designer, recently told People she plans to take time off once the baby arrives. "More important than anything is that I have a peaceful life and a peaceful home," she said.

Click here to read more in OK! magazine