Gestational Vitamin D and offspring bone measures; does maternal bone quality mediate the association? — ASN Events
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Gestational Vitamin D and offspring bone measures; does maternal bone quality mediate the association? (#234)

Natalie Hyde 1 2 , Sharon L Brennan 3 4 5 , John D Wark 2 , Sarah M Hosking 1 , Julie A Pasco 1 5
  1. School of Medicine, Deakin University, Geelong, Australia
  2. Bone and Mineral Medicine, Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia
  3. Australian Institute for Musculoskeletal Sciences, The University of Melbourne, St. Albans, Victoria, Australia
  4. Institute of Health and Ageing, Australian Catholic University, Melbourne, Victoria, Australia
  5. Melbourne Medical School-Western Campus, The University of Melbourne, St. Albans, Victoria, Australia

Some observational evidence suggests a potential association between maternal vitamin D during pregnancy and offspring bone measures. Shared genetics and environmental factors might confound this association thus we aimed to determine if the association is mediated by maternal bone quality.

Pregnant women were recruited as part of the Vitamin D in Pregnancy study from the University Hospital Geelong (2002-03) and had serum samples collected both at recruitment (before 16 weeks gestation) and 28-32 weeks gestation. Vitamin D (25OHD) was assessed by radioimmunoassay (Immunodiagnostic Systems). Two hundred and ten mother-child pairs of the original 402 pairs (51.7%) were re-assessed when offspring were aged approximately 11 years. Maternal and offspring bone quality was assessed for 168 pairs at the calcaneus using quantitative ultrasound (QUS, Lunar Achilles) in terms of speed of sound (SOS), broadband ultrasound attenuation (BUA) and stiffness index (SI).

In adjusted models maternal 25(OH)D at recruitment was associated with offspring SOS (β 1.6 95% CI 0.2,3.1) and, in boys only, with SI (β 1.0 95% CI 0.1, 1.8). These relationships remained independent of maternal QUS parameters (β 1.7 95% CI 0.3, 3.1) and (β 0.9 95% CI 0.1, 1.6), respectively. No associations were detected for BUA. Furthermore there were no associations with and QUS parameter and maternal 25(OH)D at 28-32 weeks.

These prospective data support prior evidence of a relationship between maternal 25(OH)D levels during early pregnancy and measures of bone health in their offspring. Importantly, these associations were independent of maternal QUS parameters, suggesting that the relationship between gestational vitamin D status and offspring bone health is at least partly independent of maternal bone phenotype.