Vanishing triplet (one or more embryos resorbed in a triplet pregnancy) occurs in roughly 50% of cases that start with three gestational sacs. Natural triplet pregnancies are already rare at about 1 in 7,000โ8,000. Relative to all worldwide pregnancies this is uncommonโon the order of 1 in several thousand to 10,000 overall, though rates rise with IVF/ART.