Gestational diabetes mellitus (GDM) represents an intersection between pregnancy and T2DM; both states impacting bone density (BMD) and structure. We aimed to identify factors influencing bone health after GDM pregnancy. In a longitudinal, observational study of women post-GDM, anthropometric measurements, biochemistry, DXA and lifestyle questionnaires were completed at 3 and 12 months postpartum. Data from 101 women were analysed.
At 3 months postpartum, mean Z-scores for the lumbar spine BMD (LS) (-0.49 ± 1.00 [SD]), femoral neck (FN) (-0.29 ± 0.91), and TBS (-0.51 ± 1.08) were below the expected mean of zero. At 12 months postpartum, BMD and TBS Z-scores improved but remained below zero: LS -0.27 ± 1.02, FN -0.26 ± 0.92, and TBS -0.40 ± 0.97.
At 12 months, despite positive correlation between BMI and absolute BMD, there was inverse relationship between BMI and Z-scores at the LS (r=-0.2, p0.04). Furthermore, we observed a significant negative correlation between total-body fat percentage and Z-scores at LS (r=-0.31, p=0.001) and FN (r=-0.23, p=0.02), and between central fat percentage and Z-scores at LS (r=-0.28, p=0.005) and FN Z-score (r=-0.21, p=0.04). Change in total-body fat% from 3 to 12 months was negatively correlated with change in LS Z-score (r=-0.275, p=0.006) and FN Z-score (r=-0.412, p<0.001). Similar relationships were observed for change in BMI, but not change in central fat%.
At 12 months, women with vitamin D>50 nmol/L had significantly higher LS BMD (1.22 vs 1.15 g/cm2, p=0.004) and LS Z-score (-0.02 vs -0.73, p=0.0006) but there was no FN difference. There was no significant relationship between change in BMD Z-scores and calcium intake, vitamin D, exercise intensity or diabetes status at 12 months. Breastfeeding significantly impacted change in FN absolute BMD.
No consistent associations with TBS Z-scores were observed.
Conclusion: increased adiposity predicts slower recovery of BMD post GDM pregnancy.