Bone Mineral Density Changes in Pregnancies with Gestational Hypertension: a Longitudinal Study Using Quantitative Ultrasound Measurements

Objective: To compare the maternal bone mineral density (BMD) changes in gestational hypertensive and normotensive pregnancies using quantitative ultrasound.

Methods: Consecutive patients were recruited from a general obstetric clinic over a period of 9 months. BMD measurements were performed at the os calcis in early pregnancy before 20 weeks and in the late third trimester after 36 weeks, using a Hologic Sahara Clinical Bone Sonometer system. These patients were followed up in accordance with standard antenatal protocol. The diagnosis of gestational hypertension (GH) was made based on a standard institutional protocol. The changes in BMD from early to late pregnancy were compared between those with/without GH.

Results: A total of 450 patients with complete data were analyzed. The overall incidence of GH was 4.8% (n = 22), of which 1.7% (n = 8) fulfilled the definitions of severe pre-eclampsia. A mean BMD loss of 0.0382 g/cm2 (around 6% of early pregnancy BMD) [corrected] was demonstrable from early to late gestation The hypertensive group has marginally higher mean BMD loss as compared to the normotensive group (0.052 vs. 0.037 g/cm²; P = 0.037). However, regression analysis models showed that early pregnancy BMD values, early pregnancy fat percentage and fat accumulation in pregnancy were significant factors affecting BMD loss during pregnancy, while GH was not in the equations.

Conclusion: The development of gestational hypertensive disorders apparently does not have any significant impact on BMD changes during pregnancy.