DEAD BY FIVE
Sometimes children were exhibited for profit but for various reasons died young
The child who became known as "the beautiful spotted negro boy"  was born on the island of St. Vincent in 1808. His father and mother were Africans and "both perfectly black."  He was taken to Bristol, England at the age of 15 months and exhibited by John Richardson at great profit. Richardson had the baby christened George Alexander Grattan and treated the child well, perhaps even as his own. George Alexander was one of the last oddities to be exhibited at Bartholomew's Fair before it fell into disrepute.
Little George died before his fifth birthday of a jaw infection and is buried at Great Marlow, Buckinghamshire, England.
This boy child was born in 1783 at Mandalgent near Bardawan in Bengal, India. He was perhaps the first recorded case of the condition now known as "craniopagus parasiticus". He was exhibited by his parents in the streets of Calcutta whence he came to the attention of English anatomist Sir Everard Home. In a letter Home wrote to the surgeon John Hunter he mentions that "when it was a little over the age of two years, the mother went out to fetch some water and upon her return found the child dead from the bite of a cobra da capello." The double skulls are now preserved at the  Museum of the Royal College of Surgeons in the U.K.
There appears to be disagreement as to the age of Caroline Crachami, the Sicilian Fairy, at the time of her death. One account published in the American Journal of Medical Genetics concludes that her dental age [3 years +/- 6 months] was similar to her chronological age but Jan Bondeson argues that her medical condition would cause her dentition to appear to be that of 3 year old when in fact she was nine years old when she died in 1824.
The "Sardinia Sisters" Rita and Christina Parodi were born in Italy in 1829.  As soon as the babies were physically able to travel, Mom and Dad took them to Paris to be exhibited but the authorities would not approve of any public exhibiton so the babies were shown privately. The little  girls  died at the tender  age of  8 months supposedly  from "overexposure".   I believe their skeleton(s)  is conserved at the Museum of Natural History in Paris.
Babies with hydrocephalus were exhibited for profit but never lived long
These babies known only as the Jones twins were born in June of 1889. When on exhibiton in Buffalo, N.Y. they contracted measles followed by  acute bronchitis. They died hours apart in February 1890 at the age of eight months.
These two little girls are Mina and Minnie Finley and were born near Mt. Gilead, Ohio in 1870. They began to be exhibited at age five months around the U.S. and it was while on tour that Mina contracted cholera. Her sister weakened and died first however, Mina followed an hour later.  For a while they continued to be exhibited in a casket with a glass top but were later buried.
Danny and Donny Hartley were never exhibited but Dad said he might reconsider when the boys got a little older. He never had the chance, though, because the twins  died before their first b-day in 1954.
Rosa and Marie Drouin were born in St. Benoit, Quebec, Canada in 1877. It appears their parents began to exhibit them at the age of seven months. They were proclaimed to be even more remarkable than the Siamese Twins (who died in 1874). The little girls became so well-known and regarded that even Barnum sought to employ them but I don't know if he ever had a hand in their exhibition. The twins died quietly and without fanfare at the age of seventeen months reportedly from  a bad cold.