Three-year-old Trevor King of Arlington still goes back to the nursery and counts when someone asks him how many babies his mother brought home from Fairfax Hospital two months ago.

"One, two, three, four . . . " Trevor counts as he points to Christopher, Geoffrey, Erik, and Mary, sleeping two to a crib.

"Mommy has four babies," he says, racing into the living room of his South Arlington home to find his mother and reach for the locket around her neck with his picture in it. "That's the hardest part," said Susan King, 32, yesterday, "making sure that Trevor gets enough attention. It's not easy when you have quadruplets."

The reality of having four babies at once is slowing sinking in, she said, estimating that they go through 50 diapers, five loads of clothes, and forty 4 oz. bottles of formula each day.

"It was a miracle," said King, about her three identical blond-haired sons and dark-haired daughter. Quadruplets occur without the use of fertility drugs approximately 1 in every 658,500 births, according to Dr. Donald Keith, director of the Center for the Study of Multiple Birth in Chicago.

The real miracle, according to friends at a reception for the King quads yesterday at the Fairlington Community Center, is not that the quadruplets were born, but that the Kings wouldn't mind having more children. "No, I'm not closing the book on having more," said King, a former X-ray technician who stays home and cares for the children. "I love being pregnant."

Even though she was bedridden for the four months prior to the births, she said, "Feeling those kids kicking around inside me was terrific." Her husband, Geoffrey King, 34, a real estate agent, agrees that "they are not ruling out the chance of having more" even though their two-bedroom Fairlington condominium is getting crowded.

With no family history of multiple births, Susan King said she doesn't believe she could have more than one child the next time, but she laughed, "You never know." Though the quads were expected at yesterday's reception given by Webster Realty, King's Alexandria employer, the cold weather kept them home.

Two of the babies, who each weigh close to 8 pounds -- twice their birth weight -- have irregular heart beats and are monitored constantly by an electronic device taped to their chest. In six or seven months, Susan King hopes that the heart problem will be corrected.

Geoffrey King says he tries not to worry about matters like the cost of four children going to college at once. "I want to enjoy them now." He says sometimes when he sees the four lined up in a row, he thinks he's in a toy store: "They look like they're on a shelf, three of one kind and one of another. You know, it's still hard to believe they're real."