A US woman has naturally conceived and given birth to a healthy set of triplets, a rare pregnancy that medical professionals described as an uncommon occurrence. Nyla Craft from South Bay region in Los Angeles, already a mother of two — a daughter and a son — gave birth to three boys: two identical twins and a third who is their fraternal sibling, said chief of neonatology Dr Rohit Passi at Kaiser Permanente South Bay Medical Center, as reported by the Los Angeles Times. “This is a very rare pregnancy and a rare outcome,” Passi said. Triplets Conceived Naturally The triplets were conceived naturally, Passi said, which happens in only about one in 10,000 pregnancies. They were carried for 36 weeks, which is considered a good gestational period for triplets. All three were born at a healthy weight, with a combined weight of about 19 pounds — around three pounds short of the reported world record total weight for triplets, according to the Guinness Book of World Records.Also read: Scottish Toddler With Rare UV Disorder Gets UV-Safe Home: All About Inherited XP Pregnancy Was Physically Demanding Craft said she first learned she was expecting triplets during a doctor’s appointment earlier this year. “Earlier this year, I went to the doctor and I saw like two different sets,” she said. “I was like, oh my goodness, I’m having twins. And she was like, no, there are three. And I was like, oh my gosh, triplets.” Craft said the physical demands of carrying the triplets were unlike anything she had experienced before. When she learned the three babies weighed a combined 19 pounds at birth, the figure put her difficult pregnancy into perspective, ABC7.com reported. Rare Combination Of Identical And Fraternal Twins Quynh Vo-Hanser of Kaiser Permanente South Bay said the pregnancy was especially unusual. “This is a really rare event,” Vo-Hanser said. “This is what we would refer to as a mixed triplet. This is a spontaneous pregnancy, which meant that it was achieved naturally. And within this triplet set, there’s an identical twin set, and then the fraternal sibling.” Vo-Hanser emphasized the rarity of the birth. “Within the United States, there are 3.5 million deliveries and about 2,400 are triplets,” she said. Hospital Assembled Larger Delivery Team Read More: Fournier Gangrene: Woman Develops Rare Flesh-eating Infection After Bikini Shave, Herbal ApplicationThe rare delivery on August 18 required a larger-than-usual medical team to care for both the mother and the three babies. There were three NICU nurses, one for each baby, along with two doctors caring for the babies and additional doctors and nurses looking after Craft. “There were about 15 people in the delivery room when we normally have about five,” Passi said. Triplets Came Close To Reported World Record The trio’s combined birth weight of about 19 pounds also put them close to the reported world record for the heaviest set of triplets at birth, which stands at 22.7 pounds. The combination of a naturally conceived triplet pregnancy, an identical twin pair and a fraternal sibling, all born at 36 weeks and of the same sex, made the delivery particularly unusual, according to the medical team.