Influence of pregnancy on bone density: a risk factor for osteoporosis? Measurements of the calcaneus by ultrasonometry

Radiofrequency echographic multi spectrometry (REMS) in the diagnosis and management of osteoporosis: state of the art

Radiofrequency Echographic Multi Spectrometry (REMS) is a radiation-free, portable technology, which can be used for the assessment and monitoring of osteoporosis at the lumbar spine and femoral neck and may facilitate wider access to axial BMD measurement compared with standard dual-energy x-ray absorptiometry (DXA).There is a growing literature demonstrating a strong correlation between DXA and REMS measures of BMD and further work supporting 5-year prediction of fracture using the REMS Fragility Score, which provides a measure of bone quality (in addition to the quantitative measure of BMD).The non-ionising radiation emitted by REMS allows it to be used in previously underserved populations including pregnant women and children and may facilitate more frequent measurement of BMD.The portability of the device means that it can be deployed to measure BMD for frail patients at the bedside (avoiding the complications in transfer and positioning which can occur with DXA), in primary care, the emergency department, low-resource settings and even at home.The current evidence base supports the technology as a useful tool in the management of osteoporosis as an alternative to DXA.

Longitudinal changes of the femoral bone mineral density from first to third trimester of pregnancy: bone health assessment by means of non-ionizing REMS technology

BACKGROUND

Throughout the pregnancy, there is a substantial transfer of calcium from the maternal skeleton to the fetus, which leads to a transient net reduction of the maternal bone mineral density.

AIMS

To assess longitudinally the changes in the bone mineral density at the femoral neck between the first and third trimester of pregnancy in a cohort of healthy participants using Radiofrequency Echographic Multi Spectrometry (REMS) technology.

METHODS

Prospective, cohort study conducted at the University hospital of Parma, Italy between July 2022 and February 2023. We recruited healthy participants with an uncomplicated singleton pregnancy before 14 completed weeks of gestation. All included participants were submitted to a sonographic examination of the femoral neck to assess the bone mineral density (and the corresponding Z-score values) using REMS at 11-13 and 36-38 weeks of pregnancy. The primary outcome was the change in the bone mineral density values at the maternal femoral neck between the first and third trimester of pregnancy.

RESULTS

Over a period of 7 months, a total of 65 participants underwent bone mineral density measurement at the femoral neck at first and third trimester of the pregnancy using REMS. A significant reduction of the bone mineral density at the femoral neck (0.723 ± 0.069 vs 0.709 ± 0.069 g/cm2; p < 0.001) was noted with a mean bone mineral density change of - 1.9 ± 0.6% between the first and third trimester of pregnancy. At multivariable linear regression analysis, none of the demographic or clinical variables of the study population proved to be independently associated with the maternal bone mineral density changes at the femoral neck.

CONCLUSIONS

Our study conducted on a cohort of healthy participants with uncomplicated pregnancy demonstrates that there is a significant reduction of bone mineral density at femoral neck from early to late gestation.

Modulatory role of genistein on placenta and maternal bone minerals composition: further insight into its influence on pregnancy and foetal development

Pregnancy is a crucial period with an increased need to supply necessary minerals for both the mother and the developing foetus and with a tendency of altering the maternal bone mineral density when there is no balance between demand and supply of these minerals. This study evaluated the influence of genistein on the maternal bone and placenta mineral composition. Pregnant rats were grouped into control, 2 mg/kg and 4 mg/kg genistein groups, dosed accordingly till sacrificed at different gestation days (GD). Body and placenta weights, right femur bone and placenta mineral composition were analysed. A significant decrease in body weight and percentage relative right femur bone weight at GD-20 was recorded in the 2-mg group with the reverse occurring in the 4-mg genistein group. The right femur bone Ca²⁺ and Zn²⁺ was reduced towards GD-20 in both 2-mg and 4-mg genistein groups. Genistein had no influence on placenta selenium and cadmium level, but significantly decreased zinc and lead level concentration as the gestation progressed towards GD-20. Copper level was increased at GD-16 at the doses used. Genistein modulated maternal bone mineral composition and placenta capability in retaining some heavy metals at various stages of pregnancy.

Daily physical activity is associated with increased sonographically measured bone status during lactation

Objectives:

The purpose of this cross-sectional study was to investigate the association between daily physical activity and sonographically measured bone status among women during the lactation period.

Methods:

Final participants were 152 women 4 months after childbirth. Bone status of the participants was measured using quantitative ultrasonometry of the calcaneus (speed of sound). Daily physical activity was assessed using the Japanese version of International Physical Activity Questionnaire short version. After getting the International Physical Activity Questionnaire results, we classified participants into three categories (low/moderate/high) according to a protocol. Participants categorized into the low group according to the International Physical Activity Questionnaire were considered to be in the low physical activity group and those categorized into the moderate and high groups were considered to be in the moderate to vigorous physical activity group.

Results:

Speed of sound was significantly higher in the moderate to vigorous physical activity group (moderate to vigorous physical activity versus low physical activity, 1533 m/s versus 1523 m/s, p = 0.03). Daily physical activity was significantly associated with speed of sound, even after adjustment for confounding factors and prognosticators (β = 0.195, p = 0.02).

Conclusion:

Sonographically measured bone status was significantly higher in women who were physically active than in those who were physically inactive, suggesting that daily physical activity might help to maintain good bone status.

25-Hydroxyvitamin D profiles and maternal bone mass during pregnancy and lactation in Japanese women

Vitamin D deficiency is observed worldwide and represents a health hazard for mothers, infants and elderly persons. We know that many young Japanese women experience vitamin D insufficiency; however, there is a lack of knowledge regarding the serum 25-hydroxyvitamin D [25(OH)D] profile of pregnant Japanese women and of the association between maternal 25(OH)D level and maternal bone mass during pregnancy and lactation. In this longitudinal study, 160 pregnant Japanese women were enrolled; of them, 68 have been followed-up from the first trimester through at least 1 year of breast-feeding. We estimated serum 25(OH)D levels, intact PTH levels, calcaneus quantitative ultrasound (QUS: T score) scores, bone mineral density at the distal one-third of the radius, dietary intakes according to the Food Frequency Questionnaire, and sunlight exposure times. We found that Vitamin D deficiency is prevalent in Japanese women, irrespective of pregnancy or lactation, and our analysis suggested that 25(OH)D levels and BMI in the first trimester were related to the lactating women's bone mass from after delivery to 1 year after delivery.

Computing the Z Score and Centiles for Cross-sectional Analysis: A Practical Approach

Although Z scores have been reported in the literature, one of the problems for the nonstatistician is understanding the systematic approach used to compute the predicted mean and standard deviation, components of the Z score equation, which may vary as the independent variable changes over time (eg, gestational age). This review focuses on a step-by-step analysis using linear, quadratic, and fractional polynomials to compute the mean and standard deviation as a function of a continuous independent variable. Once the mean and standard deviation are computed, the Z score and centile can be derived and Z score calculators created that enable investigators to implement the results in the laboratory and/or clinical setting.

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ∼30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.

Bone metabolic changes during pregnancy: a period of vulnerability to osteoporosis and fracture

Changes in bone density and bone markers suggest that pregnancy is associated with deterioration of bone mass in the mother. The metabolism of calcium resets to allow for the needs imposed by the building of the fetal skeleton. The fetus contributes to the process through the output of regulators from the placenta. Understanding of the whole process is limited, but some changes are unambiguous. There is an increase in the circulating levels of vitamin D, but its functional impact is unclear. Fetal parathyroid hormone (PTH) and PTH-related peptide (PTHrp) play an indirect role through support of a calcium gradient that creates hypercalcemia in the fetus. Placental GH, which increases up to the end of pregnancy, may exert some anabolic effects, either directly or through the regulation of the IGF1 production. Other key regulators of bone metabolism, such as estrogens or prolactin, are elevated during pregnancy, but their role is uncertain. An increase in the ratio of receptor activator of nuclear factor kappa B ligand (RANKL) to osteoprotegerin (OPG) acts as an additional pro-resorbing factor in bone. The increase in bone resorption may lead to osteoporosis and fragility fracture, which have been diagnosed, although rarely. However, the condition is transitory as long-term studies do not link the number of pregnancies with osteoporosis. Prevention is limited by the lack of identifiable risk factors. When fractures are diagnosed, rest, analgesics, or, when indicated, orthopedic intervention have demonstrated efficacy. Systemic treatment with anti-osteoporotic drugs is effective, but the potential harm to the fetus imposes caution in their use.

Bone mineral density in gravida: effect of pregnancies and breast-feeding in women of differing ages and parity

Changes of bone during pregnancy and during lactation evaluated by bone mineral density (BMD) may have implications for risk of osteoporosis and fractures. We studied BMD in women of differing ages, parity, and lactation histories immediately postpartum for BMD, T-scores, and Z-scores. Institutional Review Board approval was received. All women while still in hospital postpartum were asked to participate. BMD was performed by dual-energy X-ray absorptiometry (DXA) machine at femoral neck (FN) and lumbar spine (LS) by a single technician. Of 132 participants, 73 (55.3%) were ≤30 years; 27 (20.5%) were primiparous; 36 (27.3%) were grand multiparous; 35 (26.5%) never breast fed. Mean FN T-scores and Z-scores were higher than respective mean LS scores, but all means were within the normal limits. Mean LS T-scores and Z-scores were highest in the grand multiparas. There were only 2 (1.5%) outliers with low Z-scores. We conclude that, in a large cohort of Israeli women with BMD parameters assessed by DXA within two days postpartum, mean T-scores and Z-scores at both the LS and FN were within normal limits regardless of age (20-46 years), parity (1-13 viable births), and history of either no or prolonged months of lactation (up to 11.25 years).

Antiretroviral therapy and pregnancy: effect on cortical bone status of human immunodeficiency virus-infected Caucasian women as assessed by quantitative ultrasonography

Treatment with antiretroviral agents (ARVs) during pregnancy is important to prevent mother-to-child transmission of the human immunodeficiency virus (HIV), but their use has been associated with low bone mineral density in adult patients. Currently, there are no data regarding the bone status of HIV-infected women who received ARV during pregnancy. The aim of this study was to evaluate cortical bone status at delivery in a group of HIV-infected women who received ARV during pregnancy and to monitor the changes occurring during the first year postpartum. We studied 33 HIV-infected and 116 HIV-uninfected healthy Caucasian women within 4 days from delivery. Follow-up measurements were performed at 4 and 12 months postpartum in 17 HIV-infected and 55 healthy women. Cortical bone status was evaluated by quantitative ultrasonography at the mid-tibia, and bone measurements were expressed as the speed of sound (SOS). HIV-infected women after delivery had a median SOS of 3,985 (3,567-4,242) m/s, while the median SOS of healthy women was 4,025 (3,643-4,250) m/s. The difference was not significant (t = 0.39, P = 0.69). No significant differences were observed between ARV-exposed and control subjects at 4 and 12 months. Our data suggest that ARV during pregnancy and the first year after delivery does not affect negatively cortical bone status.