It was a true mid-air miracle on Sunday -- a healthy baby boy was delivered on board a transatlantic United Airlines flight.
The mother was traveling from Accra, Ghana, to Washington, D.C., when she started having contractions. She wasn't expecting to deliver until late February, but the flight was halfway across the Atlantic when she went into labor.
Dr. Stephen Ansah-Addo, a dermatology resident at the University of Michigan, heard the overhead call for a health care professional and jumped into action.
He was joined by a nurse from Dayton, Ohio, and another United flight attendant, who is also a nurse.
They turned the area behind business class into an operation room of sorts -- putting down blankets and towels. The mother's contractions were getting stronger and more frequent, and after just an hour, Ansah-Addo felt the baby's head.
"I couldn't believe it was happening," he told ABC News. "But I was trying to stay calm."
A few pushes later, a healthy baby boy was crying on board.
The makeshift medical team couldn't find a clamp at first to cut the umbilical cord, so they resorted to using string.
"This is the reason why you go into medicine, to help people," Ansah-Addo said. "This is someone that really needed help, because there was nobody else there. This is the kind of medicine where you can make a difference in people's lives."
MORE: Baby born on flight in Alaska is named Sky by his motherParamedics were ready to meet the plane when the almost 12-hour flight landed at Dulles International Airport in D.C.
"The delivery was uneventful other than being at 30,000 feet," United Airlines said in a statement to ABC News.
One United employee greeted the mother with a balloon and handwritten card that read: "On behalf of the United team at Washington Dulles, congratulations on your baby boy!"
Sunday's delivery is not the first time a baby has been born in mid-air.
In April, somewhere over the Pacific, a woman who didn't know she was pregnant gave birth to a baby boy on a Delta Air Lines flight.
MORE: Woman gives birth on flight to Hawaii with help of doctor, NICU nursesLavinia "Lavi" Mounga was flying from Salt Lake City to Honolulu for a vacation when she gave birth to her son, Raymond.
He arrived early at just 29 weeks gestation.
A doctor from Hawaii and three neonatal intensive care unit nurses from North Kansas City Hospital were also on board to help Mounga deliver her baby.
They described how challenging it was to care for both patients in the small confined space of an airplane. They also had to improvise on tools, using shoelaces to tie and cut the umbilical cord and an Apple Watch to monitor the baby's heart rate.
Many U.S. airlines do not allow women to fly domestically after they are 36 weeks pregnant. Some international flights will restrict travel after 28 weeks.
ABC News' Sam Sweeney contributed to this report.