Pinckert, 53, specializes in high-risk pregnancies — multiple or premature births. He is the founder of Silver Spring and Rockville-based Greater Washington Maternal-Fetal Medicine and Genetics. He is also the director of maternal-fetal medicine at Holy Cross Hospital and chairman of Shady Grove Adventist Hospital’s obstetrics and gynecology department.

Pinckert, along with one of his patients, was featured on a National Geographic special called ‘‘In the Womb: Multiples,” that aired Jan. 14 on the National Geographic Channel.

‘‘A patient approached us [about the special],” said Pinckert, a Potomac resident. ‘‘She had been on one of the online support groups for women with a high number of multiples — three, four or five — and was approached by National Geographic.”

That woman, Garrett Park’s Jennifer Clapp-Bennett, had an unusual pregnancy, Pinckert said. She had triplets without the use of fertility drugs. Two were identical and one was fraternal. She agreed to have her pregnancy filmed and Pinckert also agreed to participate, along with Clapp-Bennett’s regular obstetrician, Dr. Richard Margolis.

It was fun, Pinckert said, and interesting to see technology used. National Geographic used 4-D ultrasound technology that made it look like the cameras were actually inside the uterus.

‘‘It looked amazingly accurate,” Pinckert said. ‘‘I looked at it and said, ‘Wow, that’s really neat.’”

So did Clapp-Bennett, who said she appreciated Pinckert’s support throughout her pregnancy and his excitement about being a part of her children’s birth.

‘‘I wasn’t just a patient,” she said. ‘‘I felt like we were a part of a family. They [Pinckert and Margolis] were as excited as I was.”

Margolis referred her to Pinckert, Clapp-Bennett said, and she was impressed by his credentials and his manner.

‘‘I really felt God pointed me to him,” she said.

Pinckert, a zoology major in college, said he has always been interested in births and multiple births.

‘‘I was interested in the whole process of how does it work so well,” he said. In medical school, he focused on obstetrics and gynecology because ‘‘it was mostly happy. On the oncology rotations, most people passed away due to tumors. It was kind of a sad place to work.”

That doesn’t mean the job isn’t challenging. When patients are referred to Pinckert, it is often a stressful and fearful time.

‘‘It’s not a perfect system,” Pinckert said of pregnancy. ‘‘Pregnancy and health aren’t really things we can choose.”

However, he said, compassion can put minds at ease. Two of Pinckert’s own children had difficult births. His first son was born three months premature and his daughter was born seven weeks premature. He can relate to what his patients are going through, and feels as happy as his patients do when babies who have some difficulties at birth go on to be happy and healthy.

‘‘It’s a very humbling job,” Pinckert said.

Pinckert delivers 12 to 15 sets of triplets a year, and usually one set of quadruplets a year. Most quadruplets and triplets, he said, are the result of fertility treatment. However, he added, one of his patients had a set of natural triplets and, later, a set of natural twins.

He delivers fewer twins only because most general practitioners are comfortable delivering them. When Pinckert steps in to help deliver twins, it is usually because one of the babies is significantly smaller than the other or the mother has a history of miscarriages.

And it’s not easy. Most women with multiple babies deliver by Caesarean section, and Pinckert has to deliver the babies by feel, and keep track of which baby is which. Babies are designated by letters so parents know who is who.

Once the babies are delivered, Pinckert’s attention focuses on the mother because that is the time she is most at risk. Because her uterus has been huge — about the size of a small beach ball — she could bleed excessively if the uterus does not contract. Usually, he said, there are few complications with either the mother or the babies.

But when there are complications, Pinckert again draws on his own experiences, remembering what he found frustrating or sad.

‘‘Sometimes patients say, ‘You just don’t understand.’ I can say, ‘Let me tell you what I did.’ Suddenly, you’re not just their doctor. You’re like a friend,” Pinckert said. ‘‘... That makes me feel like we’re giving back.”

Multiples:The numbers

About 95 percent of all multiple births in the United States are twins.

34 out of every 1,000 births in the U.S. are multiples.

The probability of having triplets naturally is about one in 8,000.

A woman has an estimated one in 64 million chance of conceiving identical quadruplets.

The record number of fetuses in a human womb at one time is 15.

Source: National Geographic