Calcium metabolism in pregnancy and the perinatal period: a review

Return to Running for Postpartum Elite and Subelite Athletes

CONTEXT

There is little evidence to guide elite athletes who desire returning to competition after giving birth to a child. Ultimately, this can result in decreased performance and increased risk of injury. This paper addresses aspects that must be considered when building and monitoring a return to running program for a postpartum elite or subelite athlete, including pelvic floor and core stability, progressive reloading of the musculoskeletal system, monitoring of nutritional parameters, and considerations for lactation.

EVIDENCE ACQUISITION

PubMed and CINAHL (Cumulative Index for Nursing and Allied Health Literature) were searched with the following search strategy: (extreme sports OR elite athletes OR running OR exercise) AND (breastfeeding OR lactation OR bone density OR fetal weight OR gestational weight gain OR postpartum or post-partum OR postnatal OR post-natal OR pregnancy OR childbirth). The following information is based on best available evidence and clinical experience.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Due to the interplay between cardiovascular fitness, postpartum nutrition, lactation, and progressive reloading of the muscular and skeletal system, we propose a multimodal, multidisciplinary approach to safely and successfully allow an athlete to return to an elite level of competition.

CONCLUSION

Return to running in the postpartum period is a highly individualized process that benefits from multidisciplinary, individualized care. This includes monitoring of nutrition, core and pelvic floor function, bone reloading, muscle and tendon reloading, and breastfeeding care when applicable.

STRENGH OF RECOMMENDATION TAXONOMY (SORT)

C.

The Effects of Vegan Diet on Fetus and Maternal Health: A Review

Veganism, a way of eating that forbids goods produced from animals, is rising in acceptance around the globe. This thorough analysis investigates how a vegan diet affects fetal growth during pregnancy, highlighting the need to maintain ideal maternal nutrition. The idea of "early life programming" emphasizes how a pregnant woman's lifestyle impacts her unborn child's health. Nutrient consumption during pregnancy makes it essential to have a healthy eating routine. While a carefully thought-out vegan diet may contain all the essential nutrients, some micronutrients need special attention, which may call for supplementation. The study delves into significant findings concerning nutritional adequacy and challenges in the discussion section, highlighting nutrients like calcium, iron, omega-3 fatty acids, vitamin D, and protein. It emphasizes medical professionals' need to monitor and assist vegan expectant mothers in meeting their nutritional needs. The analysis also examines the intricate connection between a mother's health and the outcomes of vegan pregnancies, such as decreased rates of gestational diabetes and hypertension. Examining fetal growth and development further highlights the complexity of this process, as do the contradicting data on birth weights. Furthermore, early data suggest that infants born to vegan moms may benefit cognitively, but further studies are required to prove a causal relationship. In addressing ethical and environmental issues in the review's conclusion, it is acknowledged that these aspects impact pregnant women's food decisions. Given the rising popularity of veganism, it is crucial to offer trustworthy advice to expectant women who are thinking about or already following a vegan diet.

Are Twin Pregnancies at Higher Risk for Iron and Calcium Deficiency than Singleton Pregnancies?

The aim of this study was to compare the iron and calcium status in singleton and twin pregnancies and to assess whether there is an increased risk for iron and calcium deficiency in twin gestation. The study included 105 singleton and 9 twin pregnancies at or above 35 weeks of gestation. Information on prenatal supplementation with iron or calcium was acquired, and adverse perinatal outcomes were recorded. Biosamples from all 114 mothers and 73 newborns (61 singleton and 12 twin newborns) were finally analyzed. Total iron and calcium concentrations in serum were measured through total reflection X-ray fluorescence analysis. The results indicated no significant differences in maternal serum iron and calcium concentrations between singleton and twin pregnancies. Similarly, iron and calcium concentrations in newborn umbilical cord serum samples were not different between singleton and twin pregnancies. The comparison of total iron and calcium between mothers and umbilical cord serum indicated significantly lower concentrations in the mothers, with the differences being not homogenous but rather pair-specific. A significant positive correlation between maternal serum and umbilical cord serum calcium concentration was noticed. Prenatal iron supplementation was associated with higher iron concentrations in both mothers and newborns, supporting the efficiency of supplementation and the quality of the study methods. Collectively, the data indicate no significant differences in serum iron and calcium concentrations with regard to singleton or twin pregnancies and the efficiency of iron supplementation during pregnancy for increasing iron status.

Calcium Supplementation on Glucose Tolerance, Oxidative Stress, and Reproductive Outcomes of Diabetic Rats and Their Offspring

Diabetes mellitus increases the risk of obstetric complications, morbidity, and infant mortality. Controlled nutritional therapy with micronutrients has been employed. However, the effect of calcium (Ca2+) supplementation on diabetic pregnancy is unclear. We aimed to evaluate whether diabetic rats supplemented with Ca2+ during pregnancy present better glucose tolerance, redox status, embryonic and fetal development, newborn weight, and the prooxidant and antioxidant balance of male and female pups. For this, newborn rats received the beta-cytotoxic drug streptozotocin for inducing diabetes on the day of birth. In adulthood, these rats were mated and treated with Ca2+ twice a day from day 0 to day 20 of pregnancy. On day 17, the pregnant rats were submitted to the oral glucose tolerance test (OGTT). At the end of pregnancy, they were anesthetized and killed to collect blood and pancreas samples. The uterine horns were exposed for an evaluation of maternal reproductive outcomes and embryofetal development, and the offspring's liver samples were collected for redox status measurement. Nondiabetic and diabetic rats supplemented with Ca2+ showed no influence on glucose tolerance, redox status, insulin synthesis, serum calcium levels, and embryofetal losses. The reduced rate of newborns classified as adequate for gestational age (AGA) and higher rates of LGA (large) and small (LGA) newborns and higher -SH and GSH-Px antioxidant activities in female pups were observed in diabetic dams, regardless of supplementation. Thus, maternal supplementation caused no improvement in glucose tolerance, oxidative stress biomarkers, embryofetal growth and development, and antioxidants in pups from diabetic mothers.

Pregnancy- and lactation-associated osteoporosis in the mother after the first and second children: A case report

INTRODUCTION

This study reports an unusual experience of a mother who may have developed birth-related osteoporosis after each of the births of her two children.

PRESENTATION OF CASE

A 31-year-old woman presented with lumbar back pain. She had given birth to her first child through vaginal delivery 4 months prior and was breastfeeding. Magnetic resonance imaging showed multiple fresh vertebral fractures, but continued breastfeeding resulted in further loss of bone density. The bone mineral density recovered after weaning. The patient gave birth to a second child three years after the first child's birth. She opted to discontinue breastfeeding after the detection of repeated instances of significant bone loss. No new vertebral fractures have occurred in the 9 years since the patient's initial visit to our clinic.

DISCUSSION

We describe a case where a mother experienced multiple episodes of rapid bone loss following childbirth. Bone health evaluation at an early stage following childbirth may be effective for preventing future bone fractures.

CONCLUSION

It is desirable to develop a team and guidelines for treating osteoporosis associated with pregnancy and lactation and for the next pregnancy and delivery.

Low pre-pregnant body mass index is a risk factor for the decrease of postpartum bone mineral density in systemic lupus erythematosus patients received glucocorticoid therapy

OBJECTIVES

This study investigated postpartum bone mineral density (BMD) in patients with systemic lupus erythematosus (SLE) receiving long-term glucocorticoid (GC) therapy, assessed risk factors for decreased postpartum BMD, and evaluated change of BMD after postpartum initiation or restarting of osteoporosis drugs.

METHODS

We retrospectively examined 30 SLE patients who gave birth and 31 non-pregnant SLE patients. In the postpartum SLE patients, BMD was measured after delivery and 1 year later. Multivariate analyses were performed to assess risk factors for decreased BMD in postpartum SLE patients.

RESULTS

Patient age at pregnancy was 34.5 ± 4.5 years, and SLE duration was 9.7 ± 6.0 years. The mean prednisolone dose was 9.7 ± 3.2 mg/day. Body mass index (BMI) was 21.6 ± 2.2 kg/m², with 13 women (43%) experiencing their first delivery. Postpartum BMD was 1.080 ± 0.120 g/cm² in the lumbar spine and 0.834 ± 0.109 g/cm² in the total hip. Bone loss occurred in six patients (21%) in the lumbar spine and 11 patients (37%) in the total hip. Postpartum lumbar spine BMD was significantly reduced compared to that in the non-pregnant group (1.143 ± 0.120 g/cm², p = 0.048). Multivariate analysis identified gestational age and low BMI before pregnancy as risk factors for hip bone loss.

CONCLUSION

Postpartum BMD significantly decrease in SLE patients receiving long-term GC, and low BMI before pregnancy was a risk factor for the decrease. Preconception care to prevent osteoporosis and that regularly monitors BMD after delivery are needed.

Association between parity and bone mineral density in postmenopausal women

BACKGROUND

Pregnancy has been considered a risk factor for the development of osteoporosis. Despite much research in this field, the relationship between parity and bone mineral density (BMD) is still controversial. Therefore, we conducted this study to investigate whether there was an association between parity and BMD of the femoral neck and lumbar spine in postmenopausal women.

METHODS

Cross-sectional study was conducted using data from the National Health and Nutrition Examination Survey (NHANES). Three linear regression models, Model 1 (unadjusted), Model 2 (adjusted for age and body mass index (BMI)), and Model 3 (adjusted for all covariates), were established to evaluate the relationship between parity and BMD. In addition, the p value trend of BMD in the different parity groups was mutually verified with the results of multiple regression. Multiple logistic regression models were used to assess the relationship between parity and osteoporosis.

RESULTS

In total, 924 postmenopausal women aged 45-65 years were eligible for this study. After adjustment for potential confounders, women with ≥ 6 parities had significantly lower lumbar spine BMD than women with 1-2 parities (β = - 0.072, 95% CI: - 0.125, - 0.018, P = 0.009). However, there was no correlation between parity and femoral neck BMD in any of the three regression models. Furthermore, ≥ 6 parities were associated with a significantly higher prevalence of lumbar spine osteoporosis compared with 1-2 parities (OR = 3.876, 95% CI: 1.637, 9.175, P = 0.002).

CONCLUSIONS

After adjustment for BMD-related risk factors, ≥ 6 parities were associated with decreased lumbar spine BMD but not femoral neck BMD in postmenopausal women. This suggests that postmenopausal women with high parity are at increased risk of lumbar osteoporotic fractures and should pay more attention to their bone health.

Bone metabolism and osteoporosis during pregnancy and lactation

PURPOSE

Osteoporosis in pregnancy is an uncommon disease and there is little information regarding its pathogenesis and its effects on the skeleton. This review aims to describe changes in mineral metabolism during pregnancy and lactation as well as their clinical impact.

METHODS

We performed a narrative review of the literature using the PubMed and Google Scholar databases for articles published from 1955 to 2021.

RESULTS

Mineral metabolism in the mother must adapt to the demand created by the fetus and the placenta, which together absorb calcium and other minerals from the mother to mineralize the developing fetal skeleton; analyses of iliac bone biopsies at the beginning and end of pregnancy have shown that pregnancy significantly modifies maternal bone status. The greatest demand for calcium for the maternal skeleton occurs during lactation; women who breastfeed have an even greater loss of calcium to produce milk. However, it is controversial whether breastfeeding can increase the risk of osteoporotic fractures, and the possible mechanism is considerably complicated. Osteoporosis in pregnancy is an uncommon disease characterized by the occurrence of fragility fractures, most commonly in the vertebral column, in the third trimester of pregnancy, or early postpartum. The pathogenesis of PLO remains unclear owing to its rarity; DXA provides a sensitive and specific method for diagnosing osteoporosis by measuring BMD, one of the parameters that allow a better understanding of fracture risk. One limitation is the controversy in using radiation in pregnant women and the risk to the embryo/fetus; a safe alternative can be MRI.

CONCLUSION

Pregnancy and lactation alter the maternal bone status; without a balance in metabolism, this may cause an increased risk of fracture due to changes in BMD. There is little information on BMD during pregnancy; more clinical studies are required to elucidate if this represents a risk factor for osteoporosis.

Identification and validation of key non-coding RNAs and mRNAs using co-expression network analysis in pre-eclampsia

Pre-eclampsia (PE) is a common complication of pregnancy, associated with maternal and fetal morbidity and mortality. In this study, we aimed to explore important long non-coding RNAs (lncRNAs) and their possible mechanisms in PE.GSE60438 expression profile including 25 PE samples and 23 normal samples were obtained from gene expression omnibus (GEO) database. After normalization with betaqn package in R, differentially expressed lncRNAs (DElncRNAs) and mRNAs (DEmRNAs) were identified using the limma package. Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathway were analyzed using DAVID 6.7 and GSEA 3.0. LncRNAs-mRNAs coexpression was implemented using weighted gene co-expression network analysis (WGCNA). MicroRNAs linked with these DElncRNAs and DEmRNAs were predicted and a competitive endogenous RNA (ceRNA) network was built.A total of 53 DElncRNAs and 301 DEmRNAs were identified between control and PE samples. These DEmRNAs were enriched into pathways such as protein digestion and absorption, osteoclast differentiation. WGCNA constructed a lncRNA-mRNA coexpression network, among which SUMO1P3, NACAP1, NCF1C, ANXA2P1, GTF2IP1, NAPSB, OR7E37P were hub genes. ceRNA network was constructed together with microRNAs (miRNAs), and functional analysis indicated cellular membrane and sugar binding were involved in PE progression. Five lncRNAsANXA2P1, GTF2IP1, NACAP1, NCF1C and OR7E37P were successfully validated in our clinical specimens.The DElncRNAs, including ANXA2P1, GTF2IP1, NACAP1, NCF1C and OR7E37P might play important roles in PE. However, the exact mechanism of these lncRNAs in prediction and diagnosis of PE should be further explored.

Association of ambient PM2·5 exposure with maternal bone strength in pregnant women from Mexico City: a longitudinal cohort study

BACKGROUND

Pregnancy is associated with deteriorations in maternal bone strength and heightened susceptibility to bone fractures. We aimed to investigate whether ambient particulate matter (PM)_2·5 concentrations were associated with bone strength during pregnancy.

METHODS

In this longitudinal cohort study, we analysed longitudinal data from women participating in the Programming Research in Obesity, Growth, Environment and Social Stressors (PROGRESS) cohort in Mexico City, Mexico. Eligible women were aged 18 years or older, at less than 20 weeks' gestation at the time of recruitment, planning to stay in Mexico City for the next 3 years, without heart or kidney disease, did not use steroids or anti-epileptic drugs, were not daily consumers of alcohol, and had access to a telephone. Daily ambient PM_2·5 concentrations were estimated from a spatio-temporal model that was based on the individual's address. Trabecular bone strength was measured using quantitative ultrasound from the radius of the middle finger and cortical bone strength from the proximal phalanx of the middle finger, during the second trimester, third trimester, and 1 and 6 months post partum. Bone strength T scores were modelled with PM_2·5 concentrations using linear mixed models and distributed lag models.

FINDINGS

Adjusting for multiple exposure windows, each 10 ug/m³ increase in PM_2·5 exposure concentrations in the first trimester was associated with a 0·18 SD decrease (95% CI -0·35 to -0·01; p=0·033) in ultrasound speed-of-sound (SOS) T score of trabecular bone strength from the second trimester until 6 months post partum. Similarly, each 10 μg/m³ increase in third trimester PM_2·5 exposure was associated with a 0·18 SD decrease (-0·36 to -0·01; p=0·044) in the SOS T score of trabecular bone strength from the third trimester until 6 months post partum. PM_2·5 exposure in the first month post partum was associated with a 0·20 SD decline (-0·39 to -0·01; p=0·043) in cortical bone strength until 6 months post partum.

INTERPRETATION

Ambient PM_2·5 exposure during and after pregnancy was associated with diminished trabecular and cortical bone strength. Early pregnancy PM_2·5 exposure was associated with a greater decline in bone strength later during pregnancy. Late pregnancy and early post-partum exposures adversely affected the post-partum bone strength recovery. Technological and policy solutions to reduce PM_2·5 pollution could improve public health by reducing bone fracture risk.

FUNDING

US National Institute of Environmental Health Sciences.

The inverse association between parity and bone health is independent of lifestyle in postmenopausal Chinese women

This study aimed to investigate the association between parity and bone mineral density in postmenopausal Chinese women, as well as the interference of physical activity and sedentary time on this association. A total of 1,712 participants were enrolled in this study. Participants were separated into three groups according to the number of parities: group 1, 1-2; group 2, 3-4; group 3, ≥5. Physical activity level was assessed according to the International Physical Activity Questionnaire. Calcaneus bone mineral density (BMD) and bone quality were assessed by qualitative ultrasound. As a result, logistic regression showed that compared to that in group 1, the risk of fracture in group 3 was increased significantly (p < 0.001). A greater number of parities was associated with a lower BMD, broadband ultrasonic attenuation (BUA), quantitative ultrasound index (QUI), speed of sound (SOS), and T-score among the three groups after adjustment for age (All p for trend < 0.05). The number of parities was an independent factor negatively correlated with BMD, BUA, QUI, SOS and T-score (All p < 0.05). BMD, BUA, QUI, SOS, and T-score were significantly increased in the physically a participants independent of parity (all p < 0.05), and decreased in the sedentary participants independent of parity (p < 0.05, except BUA). A great number of parities was negatively associated with bone health. Physical activity was positively correlated and sedentary time was negatively correlated with bone health independent of parity.

Secondary hyperparathyroidism is associated with postpartum blood pressure in preeclamptic women and normal pregnancies

BACKGROUND

Preeclampsia has been associated with features of secondary hyperparathyroidism. In this study, we examine the relationships of calcium metabolism with blood pressure (BP) in preeclamptic women and in a control group of normal (NORM) pregnancies in the postpartum.

METHODS

Sixty-three consecutive preeclamptic women (age 35 ± 6 years) were studied 4 weeks after delivery. We collected clinical and lab information on pregnancy and neonates and measured plasma and urinary calcium and phosphate, plasma parathyroid hormone (PTH) and 25-hydroxy vitamin D [25(OH)D], and performed 24-h ambulatory BP monitoring. BP and calcium metabolism of 51 preeclamptic were compared with 17 NORM pregnant women that matched for age, race, and postpartum BMI.

RESULTS

25(OH)D deficiency (<10 ng/ml) was found in 3% of preeclamptic women, insufficiency (10-30 ng/ml) in 67%, and NORM values (31-100 ng/ml) in the remaining 30%. Elevated plasma PTH (≥79 pg/ml) was found in 24% of preeclamptic women who had 25(OH)D plasma levels of 21.4 ± 8.3 ng/ml. In these women, PTH levels was independently associated with 24-h SBP and DBP and daytime and night-time DBP. Prevalence of nondippers and reverse dippers was elevated (75% and 33%, respectively). No associations between calcium metabolism and neonates' characteristics of preeclamptic women were observed. Prevalence of vitamin D deficiency and insufficiency and of elevated plasma PTH levels were comparable in matched groups. Considering preeclamptic women and matched controls as a whole group, office SBP and DBP levels were associated with PTH independently of preeclampsia and other confounders.

CONCLUSION

Features of secondary hyperparathyroidism are common in the postpartum. Preeclampsia and increased PTH levels were both independent factors associated with increased BP after delivery, and both might affect the future cardiovascular risk of these women.

Novel TRPV6 mutations in the spectrum of transient neonatal hyperparathyroidism

Maternal-fetal calcium (Ca2+) transport in the placenta plays a critical role in maintaining fetal bone mineralization. Mutations in the gene encoding the transient receptor potential cation channel, subfamily V, member 6 (TRPV6) have been identified as causative mutations of transient neonatal hyperparathyroidism due to insufficient maternal-fetal Ca2+ transport in the placenta. In this study, we found two novel mutations in subjects that have transient neonatal hyperparathyroidism. TRPV6 carrying the mutation p.Arg390His that localizes to the outer edge of the first transmembrane domain (S1) showed impaired trafficking to the plasma membrane, whereas TRPV6 having the mutation p.Gly291Ser in the sixth ankyrin repeat (AR) domain had channel properties that were comparable those of WT channels, although the increases in steady-state intracellular Ca2+ concentration could have led to Ca2+ overload and subsequent death of cells expressing this mutant channel. These results indicate that the AR6 domain contributes to TRPV6-mediated maintenance of intracellular Ca2+ concentrations, and that this region could play a novel role in regulating the activity of TRPV6 Ca2+-selective channels.

Maternal, placental and cordonal metallomic profiles in gestational diabetes mellitus

76 pregnant women, among them 38 affected by gestational diabetes mellitus (GDM) and 38 control subjects, were recruited at the University Hospital of Padua (Italy). Placenta samples, maternal whole blood and umbilical cord whole blood were collected after delivery and analysed via ICP-MS to determine the metallome, i.e. the whole elemental content. Results were statistically evaluated to evidence the correlation between the elemental concentrations in all samples and the presence of the disease. The results obtained in whole cord blood showed that many elements were correlated with GDM: Ca, Cu, Na, and Zn were present in higher concentration in GDM cord blood than in control samples, whereas Fe, K, Mn, P, Rb, S and Si showed an opposite trend. It was also highlighted that the cord blood from GDM patients exhibited an elemental composition more similar to that of the mother blood compared with the cord blood from control subjects. These results, in part interpreted in the light of the literature, open the possibility to use cord blood as a GDM marker, thus helping to delineate more accurate nutritional guidelines for pregnant women and to explain the biochemical processes occurring in the fetus and placenta during GDM.

Management of Endocrinopathies in Pregnancy: A Review of Current Evidence

Pregnancy in women with associated endocrine conditions is a therapeutic challenge for clinicians. These disorders may be common, such us thyroid disorders and diabetes, or rare, including adrenal and parathyroid disease and pituitary dysfunction. With the development of assisted reproductive techniques, the number of pregnancies with these conditions has increased. It is necessary to recognize symptoms and correct diagnosis for a proper pharmacotherapeutic management in order to avoid adverse side effects both in mother and fetus. This review summarizes the pharmacotherapy of these clinical situations in order to reduce maternal and fetal morbidity.

Dietary calcium status during maternal pregnancy and lactation affects lipid metabolism in mouse offspring

Calcium plays important roles in lipid metabolism and adipogenesis, but whether its status in early life affects later lipid profiles needs to be clarified. Three to four-week old C57BL/6J female mice were fed with three different reproductive diets containing normal, low (insufficient) and high (excessive) calcium concentrations respectively throughout pregnancy and lactation. At postnatal 21 days, the weaning male and female pups from each group were sacrificed for experiments and the remaining were fed with the normal chow diet for 16 weeks. Meanwhile, some of the weaning female pups from maternal low calcium diet group were fed with the normal calcium, low calcium and high calcium mature diets respectively for 8 weeks. Maternal insufficient or excessive calcium status during pregnancy and lactation programmed an abnormal expression of hepatic and adipose genes (PPAR-γ, C/EBP-α, FABP4, Fasn, UCP2, PPAR-α, HMG-Red1, Acc1, and SREBP-1c) in the offspring and this may lead to dyslipidemia and accumulation of hepatic triglyceride (TG) and total cholesterol (TC) in later life. The effects of maternal calcium status on lipid metabolism were found only in the female adult offspring, but were similar between offspring males and females at postnatal 21 days. Additionally, the dyslipidemia and hepatic lipid accumulation caused by insufficient calcium status in early life may be reversed to some extent by dietary calcium supplementation in later life.

Hypocalcemia in Pregnancy: A Clinical Review Update

Though hypocalcemia in pregnancy is not often reported in the literature, it occurs in cases of hypoparathyroidism and in mothers with severe dietary inadequacy. Hypocalcemia during pregnancy can pose numerous problems to the mother and fetus. It is associated with hypertensive disorders and can increase the risk of numerous problems such as preeclampsia and fetal growth disorders. In this review, we summarize the challenges physicians face diagnosing and managing hypocalcemia during pregnancy. A multidisciplinary team including endocrinologists and obstetricians is warranted to ensure appropriate treatment and optimal outcomes.

TRPV6 Variants Interfere with Maternal-Fetal Calcium Transport through the Placenta and Cause Transient Neonatal Hyperparathyroidism

Transient neonatal hyperparathyroidism (TNHP) is etiologically a heterogeneous condition. One of the etiologies is an insufficient maternal-fetal calcium transport through the placenta. We report six subjects with homozygous and/or compound-heterozygous mutations in the gene encoding the transient receptor potential cation channel, subfamily V, member 6 (TRPV6), an epithelial Ca²⁺-selective channel associated with this condition. Exome sequencing on two neonates with skeletal findings consistent with neonatal hyperparathyroidism identified homozygous frameshift mutations before the first transmembrane domain in a subject born to first-cousins parents of Pakistani descent as well as compound-heterozygous mutations (a combination of a frameshift mutation and an intronic mutation that alters mRNA splicing) in an individual born to a non-consanguineous couple of African descent. Subsequently, targeted mutation analysis of TRPV6 performed on four other individuals (born to non-consanguineous Japanese parents) with similar X-rays findings identified compound-heterozygous mutations. The skeletal findings improved or resolved in most subjects during the first few months of life. We identified three missense variants (at the outer edges of the second and third transmembrane domains) that alter the localization of the TRPV6: one recurrent variant at the S2-S3 loop and two recurrent variants (in the fourth ankyrin repeat domain) that impair TRPV6 stability. Compound heterozygous loss-of-function mutations for the pathogenic frameshift allele and the allele with an intronic c.607+5G>A mutation resulted in the most severe phenotype. These results suggest that TNHP is an autosomal-recessive disease caused by TRPV6 mutations that affect maternal-fetal calcium transport.

Is grand multiparity a risk factor for the development of postmenopausal osteoporosis?

Objective

In this study, we investigated the relationship between the development of postmenopausal osteoporosis and parity.

Materials and methods

The retrospective study included 129 postmenopausal women who were divided into three groups depending on the number of parity: Group I, <5; Group II, 5–9; and Group III, ≥10. The mean age of the subjects was 57.71±5.02 years.

Results

No significant difference was found among the three groups regarding body mass index values, duration of menopause, mean thyroid stimulating hormone values and frequency of diabetes. Among the three groups, no significant difference was found in terms of the frequency of lumbar osteoporosis (p>0.05), whereas a significant difference was found regarding the frequency of femoral osteoporosis (p=0.012; p<0.05).

Conclusion

It was revealed that femoral bone mineral density significantly decreased as the number of parity increased.

The Plasma Membrane Calcium ATPases and Their Role as Major New Players in Human Disease

The Ca²⁺ extrusion function of the four mammalian isoforms of the plasma membrane calcium ATPases (PMCAs) is well established. There is also ever-increasing detail known of their roles in global and local Ca²⁺ homeostasis and intracellular Ca²⁺ signaling in a wide variety of cell types and tissues. It is becoming clear that the spatiotemporal patterns of expression of the PMCAs and the fact that their abundances and relative expression levels vary from cell type to cell type both reflect and impact on their specific functions in these cells. Over recent years it has become increasingly apparent that these genes have potentially significant roles in human health and disease, with PMCAs1-4 being associated with cardiovascular diseases, deafness, autism, ataxia, adenoma, and malarial resistance. This review will bring together evidence of the variety of tissue-specific functions of PMCAs and will highlight the roles these genes play in regulating normal physiological functions and the considerable impact the genes have on human disease.

Maternal Obesity, 25-Hydroxy Vitamin D Concentration, and Bone Density in Breastfeeding Dyads

OBJECTIVE

To examine the association between maternal body mass index (BMI) and serum 25-hydroxy vitamin D [25(OH)D] concentration and bone density in mother-infant pairs.

STUDY DESIGN

The study was a secondary analysis of 234 exclusively breastfeeding dyads who were recruited in the first postpartum month for a randomized controlled trial of maternal vs infant vitamin D supplementation. Mean 25(OH)D concentrations and bone mineral density (BMD) were compared by BMI group. The adjusted association between maternal BMI and 25(OH)D and bone density was examined at 1, 4, and 7 months postpartum.

RESULTS

Obese breastfeeding women had lower 25(OH)D concentrations and higher BMD than lean women at all 3 time points (P  <  .01). Higher maternal BMI was associated with lower maternal serum levels of 25(OH)D at 1, 4, and 7 months postpartum (adjusted β = -0.45 ng/ml per kg/m², 95% CI -.076, -0.14, at 1 month) and higher BMD at the same time points (β = 0.006 BMD z score; 95% CI 0.003, 0.01 at 1 month). Seventy-six percent of infants were vitamin D deficient at 1 month of age. Infants born to overweight and obese mothers had lower 25(OH)D concentrations than infants of lean mothers (P < .01). For infants in the maternal supplementation group, higher maternal BMI was associated with lower 25(OH)D concentrations at 4 months (β = -0.68; 95% CI -1.17, -0.20) and lower bone density at 7 months (β = -0.001; 95% CI -0.002, -0.0001).

CONCLUSIONS

In exclusively breastfeeding dyads, maternal obesity is associated with lower maternal and infant serum 25(OH)D concentrations, which may impact infant bone density.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00412074.

Expression of the TRPM6 in mouse placental trophoblasts; potential role in maternal-fetal calcium transport

The placenta is required to transport calcium (Ca2+) from mother to fetus during fetal bone mineralization. In an attempt to clarify the molecular basis of Ca2+ entry for this transport, we identified TRPM6 as a candidate for apical Ca2+ entry pathway. TRPM6 mRNA increased during the last 4 days of pregnancy, coinciding with fetal bone mineralization in mice. TRPM6 mRNA and protein was localized in the trophoblasts in labyrinth where the maternal-fetal Ca2+ transport occurs. In patch-clamp recordings, we observed TRPM6/TRPM7-like currents in mouse trophoblasts after starting fetal bone mineralization but not before mineralization. Plasma membrane Ca2+ permeability was significantly increased in TRPM6/TRPM7 expressed HEK293 cells under physiological Mg2+ and ATP concentration but not in TRPM6 or TRPM7 homomer-expressing cells. These results suggest that TRPM6 is functionally expressed in mouse placental trophoblasts, implicating in maternal-fetal Ca2+ transport likely with TRPM7, which might enable to sustain fetal bone mineralization.

First-Trimester Urine Concentrations of Phthalate Metabolites and Phenols and Placenta miRNA Expression in a Cohort of U.S. Women

BACKGROUND

There is increasing concern that early-life exposure to endocrine-disrupting chemicals (EDCs) can influence the risk of disease development. Phthalates and phenols are two classes of suspected EDCs that are used in a variety of everyday consumer products, including plastics, epoxy resins, and cosmetics. In utero exposure to EDCs may affect disease propensity through epigenetic mechanisms.

OBJECTIVE

The objective of this study was to determine whether prenatal exposure to multiple EDCs is associated with changes in miRNA expression of human placenta, and whether miRNA alterations are associated with birth outcomes.

METHODS

Our study was restricted to a total of 179 women co-enrolled in the Harvard Epigenetic Birth Cohort and the Predictors of Preeclampsia Study. We analyzed associations between first-trimester urine concentrations of 8 phenols and 11 phthalate metabolites and expression of 29 candidate miRNAs in placenta by qRT-PCR.

RESULTS

For three miRNAs--miR-142-3p, miR15a-5p, and miR-185--we detected associations between Σphthalates or Σphenols on expression levels (p < 0.05). By assessing gene ontology enrichment, we determined the potential mRNA targets of these microRNAs predicted in silico were associated with several biological pathways, including the regulation of protein serine/threonine kinase activity. Four gene ontology biological processes were enriched among genes significantly correlated with the expression of miRNAs associated with EDC burden.

CONCLUSIONS

Overall, these results suggest that prenatal phenol and phthalate exposure is associated with altered miRNA expression in placenta, suggesting a potential mechanism of EDC toxicity in humans.

Current concepts in perinatal mineral metabolism

The serum levels of calcium (Ca) and phosphate are maintained higher in the fetus than in the pregnant mother, especially in late gestation, to meet the demands of fetal bone development. In order to maintain this fetal stage-specific mineral homeostasis, the placenta plays a critical role through active transcellular mineral transport. Although the molecular mechanism of transplacental Ca transport has been well studied, little is known about the transport mechanism of phosphate and magnesium. Maternal mineral homeostasis is also altered during pregnancy to supply minerals to the fetus. In the lactating mother, osteocytic osteolysis is suggested to be involved in the supply of minerals to the baby. The levels of some calcitropic and phosphotropic (Ca- and phosphate-regulating, respectively) hormones in the fetus are also different from those in the adult. The PTH level in the fetus is lower than that in the mother and nonpregnant adult. It is suggested, however, that low fetal PTH plays an important role in fetal mineral metabolism. The concentration of PTHrP in the fetus is much higher than that of PTH and plays a critical role in perinatal Ca homeostasis. Uncovering the molecular mechanisms for fetal stage-specific mineral metabolism will lead to better management of perinatal patients with mineral abnormalities.

Cross-sectional study of serum parathyroid hormone level in high-risk pregnancies as compared to nonpregnant control

OBJECTIVES

To note the value of serum parathyroid hormone (PTH) levels in normal and high-risk pregnancies (HRP) in patients attending antenatal visits at All India Institute of Medical Sciences (AIIMS).

MATERIALS AND METHODS

This is a cross-sectional study where a total of 282 patients attending Gynecology Outpatient Department at AIIMS, New Delhi were recruited. Among the 282 subjects, 251 were pregnant, and 31 were controls. The serum was tested for serum PTH levels using Beckman coulter access 2 immunoassay.

RESULTS

The median value of PTH level in pregnant women was 31.6 pg/ml with range being 0.8-505.5 pg/ml in contrast to 45.9 pg/ml with range being 19-102.7 pg/ml in nonpregnant female. This difference was statistically significant (P = 0.0012). There was no significant difference in median level of PTH in different age group. Although the median PTH levels were lower in second trimester (25.25 pg/ml) than in first trimester (35.5 pg/ml) and in third trimester (32.4 pg/ml), the difference was not statistically significant. There was no significant difference in PTH level in HRP (median value - 31.6 pg/ml) as compared to low-risk pregnancies (31.5 pg/ml).

CONCLUSION

Serum PTH levels are significantly lower during pregnancy as compared to nonpregnant state. However, age, parity, and HRP did not alter PTH level during pregnancy.

[Determinants of neonatal serum calcium in a peripheral maternity in Abidjan]

Introduction

Le transfert du calcium de la mère au nouveau-né est nécessaire pour la constitution de la charpente osseuse. L'hypocalcémie néonatale reste peu documentée en Afrique. En 1993, il a été observé au service de néonatologie du Centre hospitalo-universitaire de Yopougon à Abidjan une proportion d'hypocalcémie asymptomatique de 26.9%. L'objectif de ce travail était de préciser la prévalence de l'hypocalcémie néonatale dans une maternité périphérique de Yopougon et en déterminer les facteurs de risque.

Méthodes

Une étude transversale a été menée à la formation sanitaire de de Yopougon de février à mai 2012 auprès de 145 parturientes et leurs nouveau-nés. Les caractéristiques des mères et des nouveau-nés ont été recueillies. Les prélèvements de sang maternel et du cordon ont permis le dosage des paramètres du métabolisme phosphocalcique. Une régression linéaire multiple a été faite pour apprécier les éléments de prédilection de la calcémie néonatale.

Résultats

Les valeurs moyennes étaient de 2,271 mmol/l pour la calcémie, 1,169 mmol/l pour le phosphore, 0,735 mmol/l pour le magnésium et 69 g/l pour les protides totaux chez les mères. La durée moyenne du travail était de 499 minutes. L’âge gestationnel moyen était de 39 semaines. Les constantes anthropométriques et cliniques des nouveau-nés étaient normales. Les paramètres phosphocalciques étaient en moyenne normaux (calcémie = 2,52 mmol/l, phosphorémie = 1,668 mmol/l, magnesémie = 0,777 mmol/l, protidémie = 63 g/l). Six gestantes (4,1%) étaient hypocalcémiques contre 12 nouveau-nés (8,1%). La durée du travail influençait la calcémie néonatale (p = 0,02). En analyse multivariée, 34% de la variabilité de la calcémie néonatale était expliqué par la calcémie maternelle et la durée du travail.

Conclusion

L'hypocalcémie néonatale est rare en zone tropicale. Dans cette étude, la proportion était de 8,1%. La durée du travail influençait la calcémie néonatale. Aussi, nous recommandons de poursuivre les investigations en dosant, en plus, la vitamine D et le Parathormone de la naissance à J7 de vie et préciser les étiologies de ces hypocalcémies.

Hypoparathyroidism in pregnancy

Hypoparathyroidism is an uncommon endocrine deficiency characterised by low serum calcium, absent or inappropriately low parathyroid hormone and normal or high serum phosphorus levels. Parathyroid hormone is essential for calcium homoeostasis. Pregnancy and lactation are known for increased calcium requirement. They cause calcium stress as well as alter its metabolism. Hence, many abnormalities are expected in hypoparathyroidism during pregnancy and lactation. We report a case of pregnancy in postsurgical hypoparathyroidism, which is rarely encountered in antenatal clinics. We describe our clinical, biochemical and therapeutic experience of pregnancy and lactation in this patient with hypoparathyroidism.

Dietary calcium deficiency and excess both impact bone development and mesenchymal stem cell lineage priming in neonatal piglets

BACKGROUND

Optimizing calcium nutrition to maximize bone accretion during growth to prevent fragility fractures later in life has spurred greater interest in calcium nutrition in neonates.

OBJECTIVE

The aim of this study was to determine the effect of dietary calcium, from deficiency through excess, on bone growth, and the in vivo and in vitro behavior of mesenchymal stem cells (MSCs) in neonatal pigs.

METHODS

Twenty-four male and female piglets (24 ± 6 h old) were fed either a calcium-deficient [Ca-D; 0.6% Ca on a dry matter (DM) basis], a calcium-adequate diet (Ca-A; 0.9% Ca on a DM basis), or a calcium-excessive diet (Ca-E; 1.3% Ca on a DM basis) for 14 d to assess the impact of dietary calcium on calcium homeostasis and on the behavior of MSCs.

RESULTS

Growth rate was not affected by the Ca-E diet, although bone ash content was 16% higher (P < 0.05) and urinary calcium excretion was 5-fold higher, when normalized to creatinine, compared with the Ca-A group at trial completion. Serum parathyroid hormone (PTH) concentrations were elevated (P < 0.05) in Ca-D piglets in comparison with other groups at both 7 and 14 d. In vivo proliferation of MSCs was 30% higher (P < 0.05) in Ca-E piglets than the other groups. MSCs from both Ca-D- and Ca-E-fed piglets had greater adipogenic potential based on increased gene expression (P < 0.05) of peroxisome proliferator-activated receptor γ (Pparg) and adipocyte fatty acid-binding protein (Ap2) than MSCs from Ca-A piglets. Interestingly, only MSCs from Ca-E-fed piglets had greater (P < 0.05) gene expression of lipoprotein lipase (Lpl) during adipocytic differentiation than those from Ca-A piglets. To assess alterations in lineage allocation and priming, the most and least osteogenic (O+ and O-, respectively) and adipogenic (A+ and A-, respectively) colonies from each MSC isolation were selected on the basis of functional staining. The O+ colonies from Ca-D piglets expressed lower (P < 0.05) levels of osteocalcin (OC) mRNA than did those from other groups, whereas the O- colonies from Ca-E piglets expressed higher (P < 0.05) levels of mRNA of Pparg, Ap2, and Lpl than did those from other groups.

CONCLUSIONS

Neonatal calcium deficiency appears to reduce the osteogenic priming of MSCs while enlarging a subpopulation of potentially adipogenic cells, and excess dietary calcium appears to allow greater multipotency of MSCs. These programming alterations of MSCs could have long-term consequences for bone health.

Increase in accumulation of strontium-90 in the maternal skeleton during pregnancy and lactation: analysis of the Techa River data

The unique contamination of the Techa River (Southern Urals, Russia) in the 1950s by long-lived (90)Sr allows investigation of the accumulation of bone-seeking elements in humans. This study is based on information compiled at the Urals Research Center for Radiation Medicine (Chelyabinsk, Russia) over a long period of time. It includes the results of in vivo measurements of (90)Sr-body burden with a whole body counter (WBC), data on personal medical examinations and residence and family histories. Data on 185 women from two Techa riverside villages Muslyumovo and Brodokalmak were selected. The settlements differ in terms of (90)Sr diet intake (higher in Muslyumovo than in Brodokalmak) and ethnicity (residents were mainly Slavs in Brodokalmak and Turkic in Muslyumovo). Results of a total of 555 WBC measurements performed in 1974-1997 were available for the women studied; maximum measured values reached 40 kBq/body. The women from each settlement were subdivided into three groups according to their childbearing history: pregnancy and lactation occurred (1) during the period of maximal (90)Sr intake (1950-1951); (2) after the period of maximal intake and (3) before this period or women who were childless. An increase was found in accumulation of (90)Sr in maternal skeleton during pregnancy and lactation (group 1) by a factor of 1.5-2 in comparison with non-pregnant, non-lactating women. This result was found in both Muslyumovo and Brodokalmak samples. An increase in accumulation of toxic elements in pregnant/lactating women is associated with increased radiation/toxic doses and risk for the women's health.

The content of elements in infant formulas and drinks against mineral requirements of children

The present study aimed at analysing the content of fluorine (F), calcium (Ca), magnesium (Mg), iron (Fe) and zinc (Zn) in the drinks for children and infant formulas, a popular supplement or substitute for breast milk produced from cow milk on an industrial scale. Ca, Mg, Zn and Fe concentrations were determined using atomic absorption spectrophotometer, while F levels using a potentiometric method. F levels in the examined formula samples increased with the intended age range, until the intended age of 1 year, and then decreased. A lower content of Ca, Mg and Zn was observed in formulas intended for children <1 year of age and higher for older children. Fe content increased with the age range. A statistically significant higher content of Ca, Mg, Zn and Fe in samples intended for children with phenylketonuria in comparison to those intended for healthy children or children with food allergies was noted. The content of the analysed elements in juices and nectars showed the highest contents in products intended for infants (under 6 months of age). The lowest levels of elements tested were found in drinks for children over 6 months of age. In conclusion, the concentrations of the examined elements in infant formulas and juices for children were decidedly greater than the standards for the individual age groups. Although the absorption of these elements from artificial products is far lower than from breast milk, there is still the fear of consequences of excessive concentrations of these minerals.

Fructus ligustri lucidi ethanol extract improves bone mineral density and properties through modulating calcium absorption-related gene expression in kidney and duodenum of growing rats

Optimizing peak bone mass in early life is one of key preventive strategies against osteoporosis. Fructus ligustri lucidi (FLL), the fruit of Ligustrum lucidum Ait., is a commonly prescribed herb in many kidney-tonifying traditional Chinese medicinal formulas to alleviate osteoporosis. Previously, FLL extracts have been shown to have osteoprotective effect in aged or ovariectomized rats. In the present study, we investigated the effects of FLL ethanol extract on bone mineral density (BMD) and mechanical properties in growing male rats and explored the underlying mechanisms. Male weaning Sprague-Dawley rats were randomized into four groups and orally administrated for 4 months an AIN-93G formula-based diet supplementing with different doses of FLL ethanol extract (0.40, 0.65, and 0.90 %) or vehicle control, respectively. Then calcium balance, serum level of Ca, P, 25(OH)2D3, 1,25(OH)2D3, osteocalcin (OCN), C-terminal telopeptide of type I collagen (CTX-I), and parathyroid hormone, bone microarchitecture, and calcium absorption-related genes expression in duodenum and kidney were analyzed. The results demonstrated that FLL ethanol extract increased BMD of growing rats and improved their bone microarchitecture and mechanical properties. FLL ethanol extract altered bone turnover, as evidenced by increasing a bone formation maker, OCN, and decreasing a bone resorption maker, CTX-I. Intriguingly, both Ca absorption and Ca retention rate were elevated by FLL ethanol extract treatment, possibly through the mechanisms of up-regulating the transcriptions of calcitropic genes in kidney (1α-hydroxylase) and duodenum (vitamin D receptor, calcium transporter calbindin-D9k, and transient receptor potential vanilloid 6). In conclusion, FLL ethanol extract increased bone mass gain and improved bone properties via modulating bone turnover and up-regulating calcium absorption-related gene expression in kidney and duodenum, which could then activate 1,25(OH)2D3-dependent calcium transport in male growing rats.

Parathyroid and calcium metabolism disorders during pregnancy

Parathyroid disorders are not common among pregnant women, but harbor a significant morbidity and mortality potential if they remain unrecognized and untreated. The symptoms caused by abnormally low or high blood free calcium level are mostly non-specific in the initial stages, thus when recognized might pose a real danger. Here we will survey the alterations in calcium metabolism induced by pregnancy, and describe the clinical manifestations, diagnosis and treatment of parathyroid and other calcium metabolism disorders during pregnancy. The current literature on the impact of calcium and vitamin D deficiency during pregnancy will also be reviewed.

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.

TRPV6 and Calbindin-D9k-expression and localization in the bovine uterus and placenta during pregnancy

BACKGROUND

Transient receptor potential channel type 6 (TRPV6) and Calbindin-D9k (CaBP-9k) are involved in the active calcium (Ca2+) transport mechanism in many tissues including placenta and uterus, suggesting a role in the establishment and maintenance of pregnancy. Moreover, TRPV6 and CaBP-9k seem to support the materno-fetal Ca2+ transport that is crucial for fetal Ca2+ homeostasis, bone growth and development. However, it is unknown if these proteins are also involved in the aetiology of pathologies associated with parturition in cows, such as retained fetal membranes (RFM). The aim of the current study was to create an expression profile of uterine and placentomal TRPV6 and CaBP-9k mRNAs and proteins during pregnancy and postpartum in cows with and without fetal membrane release.

METHODS

Uteri and placentomes of 27 cows in different stages of pregnancy and placentomes of cows with and without RFM were collected. Protein and mRNA expression of TRPV6 and CaBP-9k was investigated by real-time PCR, immunohistochemistry and Western blot.

RESULTS

In the uterine endometrium, highest TRPV6 and CaBP-9k expression was found in the last trimester of pregnancy, with a particular increase of protein in the glandular epithelium. In the placentomes, a gradual increase in TRPV6 mRNA was detectable towards parturition, while protein expression did not change significantly. Placentomal CaBP-9k expression did not change significantly throughout pregnancy but immunohistochemistry revealed an increase in staining intensity in the maternal crypt epithelium. Immunohistochemical, stronger placental CaBP-9k signals were seen in animals with RFM compared to animals with an undisturbed fetal membrane release, while protein levels, measured by Western blot analyses did not change significantly.

CONCLUSIONS

The results of the present study demonstrate a dynamic expression of TRPV6 and CaBP-9k during pregnancy in the bovine uterine endometrium and placentomes, suggesting a functional role for these proteins in Ca2+ metabolism during pregnancy. The temporal and spatial expression patterns indicate that TRPV6 and CaBP-9k may be involved in materno-fetal Ca2+ transport, mainly through an interplacentomal transport, and that both proteins may participate in physiological processes that are crucial for fetal and placental development. However, neither TRPV6 nor CaBP-9k seem to be causative in the retention of fetal membranes.

Extrarenal expression of the 25-hydroxyvitamin D-1-hydroxylase

Like the vitamin D receptor (VDR), the CYP27B1-hydroxylase is expressed widely in human tissues. This expression profile establishes the potential for interaction of the VDR with the product of the CYP27B1, 1,25-dihydroxyvitamin D (1,25-(OH)(2)D), in either an intracrine or paracrine mode. This expansive expression profile also suggests that the local production and action of 1,25-(OH)(2)D to regulate VDR-directed gene expression may be similarly wide-ranging and distinct from what occurs in the kidney; the proximal renal tubular epithelial cell is the richest source of the CYP27B1 and the site for production of 1,25-(OH)(2)D destined to function as a hormone. Existence of the CYP27B1 at extrarenal sites has been widely documented, although the functional impact of the enzyme in these tissues has yet to be fully demonstrated. Two notable exceptions are the disease-activated macrophage (e.g., in sarcoidosis or tuberculosis) and the placenta. These two tissues are capable of generating enough 1,25-(OH)(2)D so as to be detectable in the general circulation. As such, this review will focus on CYP27B1 expression only at these two sites, theorizing that 1,25-(OH)(2)D production at these sites is for the purpose of local immunoregulatory function, not for controlling calcium balance in the host or the fetus.

Vitamin D, the placenta and pregnancy

Impaired vitamin D status is common to many populations around the world. However, data suggest that this is a particular problem for specific groups such as pregnant women. This has raised important questions concerning the physiological and clinical impact of low vitamin D levels during pregnancy, with implications for classical skeletal functions of vitamin D, as well as its diverse non-classical actions. The current review will discuss this with specific emphasis on the classical calciotropic effects of vitamin D as well as the less well established immunological functions of vitamin D that may influence pregnancy outcome. The review also describes the pathways that are required for metabolism and function of vitamin D, and the various clinical complications that have been linked to impaired vitamin D status during pregnancy.

Hearing loss in pregnancy

To study hearing loss in healthy pregnant women. Tertiary care hospital. Prospective study. We screened fifty healthy, non-complicated pregnant women (study group) in the third trimester for hearing loss who had no previous history for the same. Fifty healthy, non-pregnant women (control group) were also screened for hearing loss with a normal pure tone audiogram (PTA) for evidence of hearing loss. Thirteen women in the study group had evidence of hearing loss, in the form of absence of distortion product otoacoustic emission (DPOAE), though the PTA was within normal limits. In the control group, two women had evidence of hearing loss, in the form of absence of DPOAE with normal PTA. This study proves that pregnancy exacerbates hearing loss, if the patient has any risk factors for the same.

Differences in bone metabolism between singleton pregnancy and twin pregnancy

OBJECTIVE

The objective of this study was to examine the influence of twin pregnancy on calcium metabolism, including bone turnover markers and calcium-regulating factors, by comparison between singleton pregnancy and twin pregnancy in women during pregnancy and puerperium in cross-sectional and longitudinal studies.

METHODS

Women with singleton and twin pregnancies were recruited from the outpatient clinic of Tokushima University Hospital. In both cross-sectional and longitudinal studies, bone formation and resorption markers, mineral metabolism and calcium-regulating factors were measured at 10, 25, 30 and 36 weeks of pregnancy and at 4 days and 1 month postpartum in women with singleton and twin pregnancies.

RESULTS

Urinary levels of cross-linked type I collagen N-telopeptides and C-terminal telopeptides of type I collagen in women with twin pregnancy were significantly higher than those in women with singleton pregnancy and those high levels were observed earlier than those in women with singleton pregnancy. In the cross-sectional study, serum levels of bone-specific alkaline phosphatase, calcium and phosphate in women with twin pregnancy were higher and the levels of 1,25-(OH)2 vitamin D and 25-(OH) vitamin D in women with twin pregnancy were lower than those in women with singleton pregnancy.

CONCLUSION

Changes in bone metabolism in women with twin pregnancy are different from those in women with singleton pregnancy. Early and large increases in bone turnover markers allow women with twin pregnancy to meet high fetal demand for calcium during pregnancy.

Vitamin D status in pregnant Indian women across trimesters and different seasons and its correlation with neonatal serum 25-hydroxyvitamin D levels

The present cross-sectional study was conducted to determine the vitamin D status of pregnant Indian women and their breast-fed infants. Subjects were recruited from the Department of Obstetrics, Armed Forces Clinic and Army Hospital (Research and Referral), Delhi. A total of 541 apparently healthy women with uncomplicated, single, intra-uterine gestation reporting in any trimester were consecutively recruited. Of these 541 women, 299 (first trimester, ninety-seven; second trimester, 125; third trimester, seventy-seven) were recruited in summer (April–October) and 242 (first trimester, fifty-nine, second trimester, ninety-three; third trimester, ninety) were recruited in winter (November–March) to study seasonal variations in vitamin D status. Clinical, dietary, biochemical and hormonal evaluations for the Ca–vitamin D–parathormone axis were performed. A subset of 342 mother–infant pairs was re-evaluated 6 weeks postpartum. Mean serum 25-hydroxyvitamin D (25(OH)D) of pregnant women was 23·2 (sd 12·2) nmol/l. Hypovitaminosis D (25(OH)D < 50 nmol/l) was observed in 96·3 % of the subjects. Serum 25(OH)D levels were significantly lower in winter in the second and third trimesters, while serum intact parathormone (iPTH) and alkaline phosphatase levels were significantly higher in winter in all three trimesters. A significant negative correlation was found between serum 25(OH)D and iPTH in mothers (r − 0·367, P = 0·0001) and infants (r − 0·56, P = 0·0001). A strong positive correlation was observed between 25(OH)D levels of mother–infant pairs (r 0·779, P = 0·0001). A high prevalence of hypovitaminosis D was observed in pregnancy, lactation and infancy with no significant inter-trimester differences in serum 25(OH)D levels.

Maternal-fetal distribution of calcium, iron, copper, and zinc in pregnant teenagers and adults

Adolescence is marked by intensive growth and development. When pregnancy occurs during this period of the mother's growth, there is an increase in her nutritional needs. The aim of this study was to determine the levels of calcium, iron, copper, and zinc in maternal plasma, the placenta, and in the cord plasma of pregnant teenagers and adults. A total of 80 sets of maternal plasma, placentas, and cord plasma (40 from teenagers and 40 from adults) were analyzed using synchrotron radiation total reflection X-ray fluorescence. The levels of calcium, copper, and zinc in the maternal and cord plasma from teenagers were not significantly different than those from adults. Iron levels in the teenagers maternal and cord plasma were higher than in the adults. All of the minerals analyzed were present at higher levels in the placentas from adults than those from teenagers. However, the low quantities of placental calcium, iron, copper, and zinc in the teenagers do not compromise the levels of these minerals in the cord plasma. Future research regarding the placental transport of these minerals is recommended to investigate the efficiency of mechanisms of transfer of these minerals in pregnant teenagers.

Maternal circulating osteoprotegerin and soluble RANKL in pre-eclamptic women

OBJECTIVE

To evaluate alterations in the concentrations of osteoprotegerin (OPG), RANKL and the OPG/RANKL ratio in pre-eclamptic women during the puerperium.

STUDY DESIGN

This cross-sectional study was performed in the maternity ward of Aretaieio Hospital in Athens, Greece. Fifteen pregnant women with severe pre-eclampsia and 15 matched controls with premature rupture of the membranes were recruited. Fasting blood samples were obtained antepartum, immediately after diagnosing pre-eclampsia (median: 32nd gestational week), and during the 3rd-6th day postpartum, to estimate levels of circulating OPG and RANKL as well as the OPG/RANKL ratio. The anthropometric parameters evaluated included body mass index and blood pressure.

RESULTS

Mean circulating OPG levels decreased significantly in both groups in the postpartum period (controls: 43.7 ± 19.1 ng/ml vs 22.9 ± 9.1 ng/ml, p = 0.008; pre-eclamptic group: 72.3 ± 49.9 vs 49.7 ± 40.9 ng/ml, p = 0.002). The antepartum OPG/RANKL ratio was elevated in hypertensive pregnancies (2.41 ± 1.72) compared to normotensive pregnancies (1.45 ± 0.63), but the difference did not reach statistical significance (p = 0.1). The OPG/RANKL ratio decreased in the control group (0.76 ± 0.30, NS) following delivery, while it remained unchanged in the pre-eclamptic women (1.63 ± 1.40, p = 0.13). Consequently, the postpartum OPG/RANKL ratio was significantly higher in the pre-eclamptic women compared to control women (1.63 ± 1.40 vs 0.76 ± 0.30, p = 0.01). Levels of RANKL demonstrated no significant alterations during puerperium in both cases.

CONCLUSION

Pregnancies complicated with pre-eclampsia exhibit higher OPG levels and OPG/RANKL ratios, compared to control pregnancies, which might be compatible with lower bone turnover. The significance of this finding with respect to bone metabolism remains to be elucidated in larger studies.

Nutritional rickets: still a problem for the pediatric population

Rickets is a mineralization disorder of the growing bone. Nutritional rickets is still prevalent in many parts of the developing world and is re-emerging in developed countries. Although vitamin D deficiency plays a central role in the pathogenesis of this disease, calcium deficiency and genetic factors may also cause or contribute to the development of rickets. This review will focus on the classical form of nutritional rickets, in other words, vitamin D-deficiency rickets. The epidemiology, ethiopathogenesis, risk factors, clinical picture, diagnosis, treatment and prevention of nutritional rickets are reviewed.