Osteogenesis imperfecta, also known as brittle bone disease, is a genetic disorder that causes bones to break easily. Severe cases of the disease can result in hundreds of fractures during a person’s lifetime or even death. Researchers have shown that limiting a specific maternal protein in pregnant mice with osteogenesis imperfecta resulted in offspring with stronger, denser bones. The finding might one day provide a new therapeutic approach to treating brittle bone disease.