Relationship between bone mineral density changes in pregnancy and maternal and pregnancy characteristics: a longitudinal study

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.

Metal exposure and bone remodeling during pregnancy: Results from the PROGRESS cohort study

Pregnancy is characterized by high bone remodeling and might be a window of susceptibility to the toxic effects of metals on bone tissue. The aim of this study was to assess associations between metals in blood [lead (Pb), cadmium (Cd)and arsenic (As)] and bone remodeling during pregnancy. We studied pregnant woman from the PROGRESS Cohort (Programming Research in Obesity, Growth, and Environment and Social Stress). We measured concentrations of metals in blood and obtained measures of bone remodeling by quantitative ultrasound (QUS) at the radius in the second and third trimester of pregnancy. To account for chronic lead exposure, we measured lead in tibia and patella one-month postpartum with K-shell X-ray fluorescence. We assessed cross-sectional and longitudinal associations between multiple-metal concentrations and QUS z-scores using linear regression models and linear mixed models adjusted for potential confounders. Third trimester blood Cd concentrations were marginal associated with lower QUS z-scores [-0.16 (95% CI: -0.33, 0.007); P-Value = 0.06]. Mixed models showed that blood Cd was longitudinally and marginally associated with an average of -0.10 z-score (95% CI: -0.21, 0.002; P-Value = 0.06) over the course of pregnancy. Associations for Pb and As were all inverse however none reached significance. Additionally, bone Pb concentrations in patella, an index of cumulative exposure, were significantly associated with -0.06 z-score at radius (95% CI: -0.10, -0.01; P-Value = 0.03) during pregnancy. Pb and Cd blood levels are associated with lower QUS distal radius z-scores in pregnant women. Bone Pb concentrations in patella were negatively associated with z-score at radius showing the long-term effects of Pb on bone tissue. However, we cannot exclude the possibility of reverse causality for patella Pb and radius z-score associations. Our results support the importance of reducing women's metal exposure during pregnancy, as metals exposure during pregnancy may have consequences for bone strength later in life. The main finding of our study is the association between Cd blood levels and radius z-score during pregnancy. Bone lead in patella was also negatively associated with radius z-scores.

Quantitative systematic review: Methods used for the in vivo measurement of body composition in pregnancy

AIMS

Because of the increased overall prevalence of pre-pregnancy obesity among racial-ethnic groups, we conducted a review of published methods for body composition measurement during pregnancy considering at present there is no consensus on the best practices and type of study design that researchers should use for this purpose.

DESIGN

Quantitative systematic review.

DATA SOURCES

PubMed, EMBASE, Scopus, Web of Science, and Virtual Library of Health. Search dates from 1997-2016.

REVIEW METHODS

Search of articles indexed in selected databases from 1997-2016. Studies were published in English, Spanish, and Portuguese. Graphs were carried out using data visualization software.

RESULTS

From the 112 included studies, 70 were prospective cohorts, 30 cross-sectional studies, 10 randomized controlled trial, and two retrospective studies. Cross-sectional studies and randomized controlled trial depicted a positive correlation with significant trend.

CONCLUSIONS

Although several methods for body composition measurement exist, only bioelectrical impedance analysis, displacement plethysmography, and displacement plethysmography show a significant growing trend. Use of data visualization allows understanding various associations among categorical variables, with a graphical display of their multidimensional behaviour.

IMPACT

Public and private health-care institution evaluating pregnancy women. Health-care personnel, including nursing professional, dealing with measurements of body composition during pregnancy will find reading this manuscript beneficial.

Prevalence of Low Bone Mineral Density and Associated Risk Factors in Korean Puerperal Women

Although pregnancy is a medical condition that contributes to bone loss, little information is available regarding bone mineral density (BMD) in puerperal women. This cross sectional study aimed to evaluate the prevalence of low BMD in puerperal women and to identify associated risk factors. We surveyed all puerperal women who had BMD measurements taken 4-6 weeks after delivery in a tertiary university hospital, and did not have any bone loss-related comorbidities. Among the 1,561 Korean puerperal women, 566 (36.3%) had low BMD at the lumbar spine, total hip, femoral neck, and/or trochanter. Multivariate analysis revealed that underweight women had a significantly higher risk of low BMD compared with obese women at pre-pregnancy (adjusted odds ratio [aOR], 3.21; 95% confidence interval [CI], 1.83-5.63). Also, women with inadequate gestational weight gain (GWG) were 1.4 times more likely to have low BMD than women with excessive GWG (aOR, 1.42; 95% CI, 1.04-1.94). One-way ANOVA showed that BMDs at the lumbar spine and total hip were significantly different between the 4 BMI groups (both P < 0.001) and also between the 3 GWG groups (both P < 0.001). In conclusion, this study identifies a high prevalence of low BMD in puerperal women and thus suggests the need for further evaluation about the change of BMD in pregnancy and postpartum period.

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.

Effect of calcium supplementation on bone resorption in pregnancy and the early postpartum: a randomized controlled trial in Mexican women

Background

Calcium needs are physiologically upregulated during pregnancy and lactation to meet demands of the developing fetus and breastfeeding infant. Maternal calcium homeostasis is maintained by hormonal adaptive mechanisms, thus, the role of dietary calcium supplementation in altering maternal responses to fetal-infant demand for calcium is thought to be limited. However, increased calcium absorption is directly related to maternal calcium intake and dietary supplementation has been suggested to prevent transient bone loss associated with childbearing.

Methods

In a double-blind, randomized placebo-controlled trial, we randomly assigned 670 women in their first trimester of pregnancy to 1,200 mg/day calcium (N = 334) or placebo (N = 336). Subjects were followed through 1-month postpartum and the effect on urinary cross-linked N-telopeptides (NTx) of type I collagen, a specific marker of bone resorption, was evaluated using an intent-to-treat analysis. Women with a baseline and at least one follow-up measurement (N = 563; 84%) were included. Subsequent analyses were conducted stratifying subjects by compliance assessed using pill counts. In random subsets of participants, bone-specific alkaline phosphatase (BAP) (N = 100) and quantitative ultrasound (QUS) (N = 290) were also measured.

Results

Calcium was associated with an overall reduction of 15.8% in urinary NTx relative to placebo (p < 0.001). Among those who consumed ≥50%, ≥67%, and ≥75% of pills, respectively, the effect was associated with 17.3%, 21.3%, and 22.1% reductions in bone resorption (all p < 0.001). There was no significant effect of calcium on bone formation measured by BAP. However, by 1-month postpartum, those in the calcium group had significantly lower NTx/BAP ratios than those in the placebo group (p = 0.04) indicating a net reduction in bone loss in the supplement group by the end of follow-up. Among subjects who consumed ≥50% and ≥75% of pills, respectively, calcium was also associated with an increase of 26.3 m/s (p = 0.03) and 59.0 m/s (p = 0.009) in radial SOS relative to placebo by 1-month postpartum.

Conclusions

Calcium administered during pregnancy and the early postpartum period, to women with intakes around adequacy, was associated with reduced bone resorption and, thus, may constitute a practical intervention to prevent transient skeletal loss associated with childbearing.

Trial registration

ClinicalTrials.gov Identifier NCT00558623

Reductions in heel bone quality across gestation are attenuated in pregnant adolescents with higher prepregnancy weight and greater increases in PTH across gestation

Few studies have examined the effect of maternal calcium intake and vitamin D status on bone health across gestation in pregnant adolescents. This study aimed to characterize maternal bone quality and determinants of bone-quality change across gestation in pregnant adolescents. Healthy pregnant adolescents (n = 156; aged 13 to 18 years) with singleton pregnancies and at 12 to 30 weeks gestation at enrollment were recruited from two urban maternity clinics in Baltimore, MD, and Rochester, NY, for this prospective longitudinal study. Maternal serum was collected at midgestation and at delivery for assessment of bone biomarkers and calcitropic hormones. Maternal bone quality (assessed by heel ultrasound) and sonographic fetal biometry were measured up to three times across pregnancy. Racially diverse teens (64.7% African American, 35.3% white) were followed from 21.0 (interquartile range [IQR] 17.3, 27.0) weeks of gestation until delivery at 40.0 (IQR 39.0, 40.7) weeks. Significant decreases in calcaneal speed of sound (SOS), broadband ultrasound attenuation (BUA), and quantitative ultrasound index (QUI) (-9.2 ± 16.1 m/s, -3.2 (-8.0, 2.1) dB/MHz and -5.3 ± 8.8, respectively) were evident across pregnancy. Multivariate analysis controlling for baseline measures and measurement intervals was used to identify independent predictors of normalized (per week) calcaneal bone loss. Weekly decreases in bone quality were not significantly associated with maternal calcium intake or 25(OH)D concentration. Greater weekly reductions in calcaneal bone quality were evident in teens with lower prepregnancy weight (BUA, p = 0.006 and QUI, p = 0.012) and among those with lower weekly increase in PTH (SOS, p = 0.046). Overall, significant decreases in calcaneal bone quality occurred across pregnancy in adolescents, but the magnitude of this loss was attenuated in those with greater prepregnancy weight and weekly increases in PTH. Further studies are needed to understand the role of elevated PTH and greater prepregnancy weight in preserving adolescent bone during pregnancy.

Challenges in determining body fat in pregnant women

BACKGROUND/AIMS

Determining body composition in pregnant women is challenging as not all of the existing applicable methodologies can be used during pregnancy and not all of the methods have been properly standardized. The aim of this study was to compare the existing anthropometric methods for the evaluation of body composition, especially in pregnant women.

METHODS

One hundred forty-seven pregnant volunteers aged [average (SD)] 31 years (± 4) in gestational week 32 (± 3) provided information on their age and prepregnancy body mass. Their height, current mass, skinfold thicknesses, and limb circumferences were measured. The body density and fat percentage were calculated according to 17 different anthropometric equations obtained from the literature. Data were analyzed with ANOVA.

RESULTS

For the same sample of pregnant women, the body fat percentages obtained using the existing anthropometric methods varied greatly (p < 0.0001) and ranged from 16% (± 5) to 38% (± 4); methods developed specifically for pregnant women yielded disturbingly large differences, with body fat values ranging from 16% (± 5) to 36% (± 6).

CONCLUSIONS

This study revealed large discrepancies among anthropometric methods for body composition assessment in pregnant women. As the results from the same sample obtained with different existing equations are wide ranging, the existing methodologies should be examined and improved before they can serve as sources of information regarding the health status of pregnant women.

Calcium economy in human pregnancy and lactation

Pregnancy and lactation are times of additional demand for Ca. Ca is transferred across the placenta for fetal skeletal mineralisation, and supplied to the mammary gland for secretion into breast milk. In theory, these additional maternal requirements could be met through mobilisation of Ca from the skeleton, increased intestinal Ca absorption efficiency, enhanced renal Ca retention or greater dietary Ca intake. The extent to which any or all of these apply, the underpinning biological mechanisms and the possible consequences for maternal and infant bone health in the short and long term are the focus of the present review. The complexities in the methodological aspects of interpreting the literature in this area are highlighted and the inter-individual variation in the response to pregnancy and lactation is reviewed. In summary, human pregnancy and lactation are associated with changes in Ca and bone metabolism that support the transfer of Ca between mother and child. The changes generally appear to be independent of maternal Ca supply in populations where Ca intakes are close to current recommendations. Evidence suggests that the processes are physiological in humans and that they provide sufficient Ca for fetal growth and breast-milk production, without relying on an increase in dietary Ca intake or compromising long-term maternal bone health. Further research is needed to determine the limitations of the maternal response to the Ca demands of pregnancy and lactation, especially among mothers with marginal and low dietary Ca intake, and to define vitamin D adequacy for reproductive women.

Bone mineral density changes during pregnancy in actively exercising women as measured by quantitative ultrasound

Objective

To evaluate whether bone mineral density (BMD) changes in women engaged in active exercises during pregnancy would be different from non-exercising women.

Methods

Consecutive patients with singleton pregnancies who were engaged in active exercise training during pregnancy were prospectively recruited over a period of 6 months. Quantitative USG measurements of the os calcis BMD were performed at 14–20 weeks and at 36–38 weeks. These patients were compared to a control cohort of non-exercising low-risk women.

Results

A total of 24 physically active women undergoing active physical training of over 10 h per week at 20 weeks gestation and beyond (mean 13.1 h, SD 3.3) were compared to 94 non-exercising low-risk women. A marginal fall in BMD of 0.015 g/cm² (SD 0.034) was demonstrable from early to late gestation in the exercising women, which was significantly lower than that of non-exercising women (0.041 g/cm²; SD 0.042; p = 0.005). Logistic regression models confirmed that active exercises in pregnancy were significantly associated with the absence of or less BMD loss in pregnancy.

Conclusion

In women actively engaged in physical training during pregnancy, the physiological fall in BMD during pregnancy was apparently less compared to those who did not regularly exercise.

Calcium and bone metabolism disorders during pregnancy and lactation

Pregnancy and lactation cause a substantial increase in demand for calcium that is met by different maternal adaptations within each period. Intestinal calcium absorption more than doubles during pregnancy, whereas the maternal skeleton resorbs to provide most of the calcium content of breast milk during lactation. These maternal adaptations also affect the presentation, diagnosis, and management of disorders of calcium and bone metabolism. Although some women may experience fragility fractures as a consequence of pregnancy or lactation, for most women, parity and lactation do not affect the long-term risks of low bone density, osteoporosis, or fracture.

Persistence of back pain symptoms after pregnancy and bone mineral density changes as measured by quantitative ultrasound--a two year longitudinal follow up study

BACKGROUND

Previous research has shown a loss of bone mineral density (BMD) during pregnancy. This loss has been correlated to the occurrence of back pain symptoms during pregnancy. The objective of this study was to evaluate whether persistence of back pain symptoms 2 years after pregnancy could be associated with BMD changes as measured by quantitative USG of the os calcis.

METHODS

A cohort of patients who reported significant back pain symptoms during pregnancy were surveyed for persistent back pain symptoms 24 to 28 months after the index pregnancy. Os calcis BMD was measured by quantitative ultrasound and compared with the BMD values during pregnancy.

RESULTS

A cohort of 60 women who had reported significant back pain symptoms in their index pregnancy completed a 24-28 months follow-up survey and BMD reassessment. Persistence of significant back pain symptoms was seen in 24 (40%) of this cohort. These women had higher BMD loss during pregnancy compared to those without further pain (0.047 Vs 0.030 g/cm2; p = 0.03). Those that remained pain free after pregnancy appeared to have completely recovered their BMD loss in pregnancy, while those with persistent pain had lower BMD values (ΔBMD - 0.007 Vs - 0.025 g/cm2; p = 0.023) compared to their early pregnancy values.

CONCLUSION

Persistence of back pain symptoms after pregnancy could be related to an inability to recover fully from BMD loss during the index pregnancy.

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.

Bone mineral density changes in gestational diabetic pregnancies-a longitudinal study using quantitative ultrasound measurements of the os calcis

To compare the maternal bone mineral density (BMD) changes in gestational diabetic and non-diabetic pregnancies using quantitative ultrasound measurements of the os calcis, 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. Random glucose screening and direct oral glucose tolerance testing were used to diagnose gestational diabetes mellitus (GDM) according to World Health Organization criteria, which was then treated according to a standard protocol. In a cohort of 480 patients, there were 96 gestational diabetic patients (14 GDM and 82 with impaired glucose tolerance). The mean BMD loss was higher in diabetic patients compared with controls (0.038 vs. 0.025 g/cm2, p = 0.048). A regression model of all pregnancies showed that higher fat accumulation was related to lower BMD loss, but diabetic status was not in the equation. Within diabetic pregnancies, lower initial BMD values, higher fat accumulation and higher early-pregnancy body mass index were associated with lower BMD loss. While gestational diabetic women had higher BMD loss than non-diabetic women, this was apparently secondary to other anthropometric factors rather than due directly to the gestational diabetic state.

Osteoporosis: Recommendations for Resistance Exercise and Supplementation With Calcium and Vitamin D to Promote Bone Health

Hormone replacement therapy, once the gold standard for treatment of osteoporosis, is no longer a clinical option. Effective alternatives are available using resistance exercise and supplementation with calcium and vitamin D to ameliorate bone loss and promote new bone formation. This article summarizes current evidence and provides recommendations for community health nurses to develop effective plans for prevention and treatment of osteoporosis.

Calcium and bone metabolism during pregnancy and lactation

Pregnancy and lactation both place significant demands on the mother to provide sufficient calcium (among other minerals and nutrients) to the fetus and neonate. Despite facing similar demands for calcium during pregnancy and lactation, the maternal adaptations differ significantly between these two reproductive periods. Women lose 300 to 400 mg of calcium daily through breast milk, and this calcium demand is met by a 5-10% loss of skeletal mineral content during 6 months of exclusive lactation. Most importantly, the lost mineral is fully restored within a few months of weaning, such that women who have breastfed do not have a long-term deficit in skeletal mineral content. This article will review our present understanding of the adaptations in mineral metabolism that occur during pregnancy and lactation, and will focus on recent evidence that the breast itself plays a central role in regulating the adaptations during lactation.

Quantitative ultrasound at the hand phalanges in pregnancy: a longitudinal study

In the prospective study, 48 females in normal pregnancy were evaluated to determine if the presence of disturbances of maternal bone and mineral status is related to fetal and newborn growth. The aim of the study was to estimate mean and individual changes in maternal skeletal and laboratory variables during pregnancy and their correlations with fetal and newborn sizes. Maternal bone and mineral status was assessed in first, second and third trimester by quantitative ultrasound (US), or QUS, at the hand phalanges (Ad-SoS [m/s]) performed by DBM Sonic 1200 (IGEA, Carpi, Italy) and laboratory investigations were collected (serum total calcium, total alkaline phosphatase and phosphate). The hypothesis that fetus growth and sizes of the newborn may have an influence on bone and mineral status in pregnancy was tested by the correlation of ultrasonographic fetal measurements and newborn sizes with changes in maternal QUS and biochemical data. Ad-SoS decreased significantly (p < 0.00001) and alkaline phosphatase increased significantly in second and third trimester of pregnancy (p < 0.01). A decrease in Ad-SoS greater than least significant change (LSC) was observed in 22 females (46%) during pregnancy. Changes in alkaline phosphatase correlated significantly with changes in Ad-SoS (r = -0.31, p < 0.05). Fetal ultrasonographic measurements (femur length and biparietal diameter) correlated significantly with changes in alkaline phosphatase (r ranged 0.31 to 0.56, p < 0.05). No significant correlations were observed between fetal ultrasonographic measurements (femur length and biparietal diameter) and newborn size with changes in Ad-SoS. In conclusion, the study revealed considerable changes in maternal bone and mineral status in normal pregnancy.