Tom and Allison Penn have been trying for four years to have a baby, and they were stunned when told that they were expecting triplets.

The identical triplets were born Wednesday at North Shore University Hospital on Long Island – and such an event happens once in 200 million births.

Dr. Victor Klein, a specialist in multiple births and high-risk pregnancies, delivered the three boys, Logan, Eli and Collin Penn. This is the 161st delivery of triplets in 20 years for Dr. Klein. They are the first triplets known to be born in Long Island in almost 15 years.

Allison Penn, 31, was impregnated with just one embryo through in-vitro fertilization. But the embryo split in two, and than one half split again. The couple hoped to avoid multiple births, but the embryo could not be stopped from splitting once more, then splitting again.

Tom Penn is a wildlife biologist with the U.S. Fish and Wildlife Service, and his wife Allison works as an environmental educator.

During the Tuesday press conference, the couple talked about the moment when they were told they would have triplets, describing it was a “complete shock. We thought, ‘That's not possible,’” Allison Penn said. “Then Tom started laughing and I started crying. . . . I was terrified,” the Los Angeles Times reports.

“Everything we had done was to have one baby,” Tom said. “Anybody who says God doesn't have a sense of humor _ everything we did was just for having one baby, and now we have three.”

The babies were given 30% chance of all three surviving. Logan may have a problem with a non-functioning kidney, but the other two boys are healthy.

The doctors thought that it would be difficult for the parents to tell the identical triplets apart, so the boys have a dot of maroon nail polish on their fingers. Logan Thomas, who weighed 4 pounds and 12 ounces, has a mark on his thumb; Eli Kirkwood, 4 pounds, has a mark on his forefinger, and Colin McGuire, weighing 4 pounds and 11 ounces, has a polish on his middle finger, FoxNews notes.