Metabolic bone disease risk factors strongly contributing to long bone and rib fractures during early infancy: A population register study.

Background: The aim of this study was to assess the incidence of fractures in infancy, overall and by type of fracture, its association with accidents, metabolic bone disease risk factors, and abuse diagnosis.

Methods: The design was a population-based register study in Sweden. Participants: Children born 1997-2014, 0-1 years of age diagnosed with fracture-diagnosis according to International Classification of Diseases (ICD10) were retrieved from the National Patient Register and linked to the Swedish Medical Birth Register and the Death Cause Register. Main outcome measures were fractures of the skull, long bone, clavicle and ribs, categorized by age (younger or older than 6 months), and accident or not.

Findings: The incidence of fractures during infancy was 251 per 100 000 infants (n = 4663). Major fracture localisations were long bone (44·9%), skull (31·7%), and clavicle (18·6%), while rib fractures were few (1·4%). Fall accidents were reported among 71·4%. One-third occurred during the first 6 months. Metabolic bone disease risk factors, such as maternal obesity, preterm birth, vitamin D deficiency, rickets, and calcium metabolic disturbances, had increased odds of fractures of long bones and ribs in early infancy (0-6 months): birth 32-36 weeks and long bone fracture [AOR 2·13 (95%CI 1·67-2·93)] and rib fracture [AOR 4·24 (95%CI 1·40-12·8)]. Diagnosis of vitamin D deficiency/rickets/disorders of calcium metabolism had increased odds of long bone fracture [AOR 49·5 (95%CI 18·3-134)] and rib fracture [AOR 617 (95%CI 162-2506)]. Fractures without a reported accident had higher odds of metabolic risk factors than those with reported accidents. Abuse diagnosis was registered in 105 infants, with overrepresentation of preterm births, multiple births and small-for-gestational age.

Interpretation: Metabolic bone disease risk factors are strongly associated with fractures of long bone and ribs in early infancy. Fracture cases with abuse diagnosis had a metabolic bone risk factor profile.