Birth Weight Is Not Associated With Risk of Fracture: Results From Two Swedish Cohort Studies

Abstract

Development and growth in utero has been suggested to influence bone health. However, the relationship with risk of fracture in old age is largely unknown. Using Cox proportional hazards regression, we studied the association between birth weight and fractures at ages 50-94 among 10,893 men and women (48% women) from the Uppsala Birth Cohort Study (UBCoS, born 1915-29) and 1334 men from the Uppsala Longitudinal Study of Adult Men (ULSAM, born 1920-24). Measured birth weight was collected from hospital or midwives' records and fractures from the Swedish National Patient Register. We observed 2796 fractures (717 of these were hip fractures) in UBCoS and 335 fractures (102 hip fractures) in ULSAM. In UBCoS, the hazard ratio (HR) per 1 kg increase in birth weight, adjusted for sex and socioeconomic status at birth, was 1.01 [95% confidence interval (CI), 0.94-1.09] for any fracture and 1.06 (95% CI, 0.91-1.23) for hip fracture. Estimates in ULSAM were similar. We did not observe a differential association of birth weight with fractures occurring before age 70 or after age 70 years. Neither birth weight standardized for gestational age nor gestational duration was associated with fracture rate. In linear regression, birth weight was not associated with bone mineral density among 303 men who were 82-years-old in ULSAM but showed positive associations with total body bone mineral content (b per kg increase in birth weight, adjusted for social class and age, 133; 95% CI, 30-227). This association was attenuated after further adjustment for body mass index and height (b,41; 95% CI,. We conclude that birth weight is associated with bone mineral content but this association does not translate into an association with risk of fracture in men and women aged 50-94 years.

Association of Body Size at Birth and Childhood Growth With Hip Fractures in Older Age: An Exploratory Follow‐Up of the Helsinki Birth Cohort Study

“…(25,26) Further, bone structure demonstrates sexual dimorphism across the life course(27) and differences between the sexes are apparent already in newborn babies, females having smaller vertebral bodies than men even when adjusted for body size. (28) Our findings are in agreement with previous studies,(13–15) in which no associations between body size at birth and hip fractures in either sex were observed. Greater body size at birth has been found to predict higher bone mineral density(7–9) and more robust bone structure(10) in older age, which could, in theory, lead to lower risk of hip fractures.…”

“…They have found no associations between body size at birth and fractures in later life. (13–15) However, one previous study including men and women from the Helsinki Birth Cohort Study (HBCS) born 1924-1933 with follow-up up to 70 years showed that children with poorest height or weight gain during the school years (7-15 yrs.) were more likely to sustain hip fractures than those with highest gain.…”

Recent hip fracture trends in Sweden and Denmark with age-period-cohort effects

“…Birth weight for example seems important for peak BMC [44], even though a Swedish study could not find any association to adult fracture risk in a cohort of women and men born in the year 1915–1929 [45]. Nationwide birth weight data for the birth cohorts in our study are not available for Sweden or Denmark.…”

Sexual Dimorphism in Newborn Vertebrae and Its Potential Implications

“…Clues that osteoporosis may result from perturbations in the fetal programming of skeletal growth come from some, but not all, epidemiological data showing a relationship between low birth weight and future risk for lower bone mass and fragility fractures. 2–5 The importance of the fetal environment to skeletal development is further supported by reports that maternal smoking, nutrition and physical activity are linked to bone mass of the offspring at birth, 6 and that placental volume and morphology are associated with neonatal bone size and mineral content. 7 …”