after, birth. In many cases, the newborn already has multiple broken bones at the time of birth. Type II infants also exhibit severe respiratory problems, and have severely deformed bones. Sixty percent of infants die less than 24 hours after being born, and survival after the first year is extremely unlikely and normally requires mechanical ventilation. In the rare cases of infants who survive their first year of life, severe developmental and motor delays are seen; neither of two infants studied in 2019, both aged around two years, had achieved head control, and both required a ventilator to breathe. Type II is also known as the "lethal perinatal" form of OI, and is not compatible with survival into adulthood. Due to similarly severely deformed bones, sometimes infants with severe type III are wrongly initially classified as type II; once long-term survival is shown, they are considered as having type III instead. Type Collagen quantity is sufficient, but is not of a high enough quality. Clinical differentiation between types III and IV is not always simple, and is further confounded by the fact that an untreated adult with type IV may have worse symptoms than a treated adult with type III; features only found in type III are its progressively deforming nature and the presence of a face with a "triangular" appearance. Another differentiating factor between type III and IV is blue sclerae; in type III, infants commonly have blue sclerae that gradually turn white with age, but blue sclerae are not commonly seen in type IV, although they are seen in 10% of cases. OI type III causes osteopenic bones that fracture very easily, sometimes even in utero, often leading to hundreds of fractures during a lifetime; early scoliosis that progresses until puberty; dwarfism (a final adult height frequently less than ); loose joints; and possible respiratory problems due to low rib cage volume causing low lung volumes. Due to the severity of the issues with the bones, neurological and seizure disorders are more likely to develop in type III. Basilar invagination, which puts pressure on the brainstem, may cause or contribute to early death; surgical treatment of it is more complex in OI cases. Type Collagen quantity is sufficient, but is not of a high enough quality. Type IV is for cases of variable severity, which do not fit into either types III or I. While one of Sillence's