Effect of prenatal calcium supplementation on bone during pregnancy and 1 y postpartum

Vitamin D supplementation for women during pregnancy

BACKGROUND

Vitamin D supplementation during pregnancy may help improve maternal and neonatal health outcomes (such as fewer preterm birth and low birthweight babies) and reduce the risk of adverse pregnancy outcomes (such as severe postpartum haemorrhage).

OBJECTIVES

To examine whether vitamin D supplementation alone or in combination with calcium or other vitamins and minerals given to women during pregnancy can safely improve certain maternal and neonatal outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Trials Register (which includes results of comprehensive searches of CENTRAL, MEDLINE, Embase, CINAHL, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform, and relevant conference proceedings) (3 December 2022). We also searched the reference lists of retrieved studies.

SELECTION CRITERIA

Randomised and quasi-randomised trials evaluating the effect of supplementation with vitamin D alone or in combination with other micronutrients for women during pregnancy in comparison to placebo or no intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently i) assessed the eligibility of studies against the inclusion criteria, ii) assessed trustworthiness based on pre-defined criteria of scientific integrity, iii) extracted data from included studies, and iv) assessed the risk of bias of the included studies. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

The previous version of this review included 30 studies; in this update, we have removed 20 of these studies to 'awaiting classification' following assessments of trustworthiness, one study has been excluded, and one new study included. This current review has a total of 10 included studies, 117 excluded studies, 34 studies in awaiting assessment, and seven ongoing studies. We used the GRADE approach to assess the certainty of the evidence. This removal of the studies resulted in evidence that was downgraded to low-certainty or very low-certainty due to study design limitations, inconsistency between studies, and imprecision. Supplementation with vitamin D compared to no intervention or a placebo A total of eight studies involving 2313 pregnant women were included in this comparison. We assessed four studies as having a low risk of bias for most domains and four studies as having high risk or unclear risk of bias for most domains. The evidence is very uncertain about the effect of supplementation with vitamin D during pregnancy compared to placebo or no intervention on pre-eclampsia (risk ratio (RR) 0.53, 95% confidence interval (CI) 0.21 to 1.33; 1 study, 165 women), gestational diabetes (RR 0.53, 95% CI 0.03 to 8.28; 1 study, 165 women), preterm birth (< 37 weeks) (RR 0.76, 95% CI 0.25 to 2.33; 3 studies, 1368 women), nephritic syndrome (RR 0.17, 95% CI 0.01 to 4.06; 1 study, 135 women), or hypercalcaemia (1 study; no cases reported). Supplementation with vitamin D during pregnancy may reduce the risk of severe postpartum haemorrhage; however, only one study reported this outcome (RR 0.68, 95% CI 0.51 to 0.91; 1 study, 1134 women; low-certainty evidence) and may reduce the risk of low birthweight; however, the upper CI suggests that an increase in risk cannot be ruled out (RR 0.69, 95% CI 0.44 to 1.08; 3 studies, 371 infants; low-certainty evidence). Supplementation with vitamin D + calcium compared to no intervention or a placebo One study involving 84 pregnant women was included in this comparison. Overall, this study was at moderate to high risk of bias. Pre-eclampsia, gestational diabetes, and maternal adverse events were not reported. The evidence is very uncertain about the effect of supplementation with vitamin D and calcium on preterm birth (RR not estimable; very low-certainty evidence) or for low birthweight (RR 1.45, 95% CI 0.14 to 14.94; very low-certainty evidence) compared to women who received placebo or no intervention. Supplementation with vitamin D + calcium + other vitamins and minerals versus calcium + other vitamins and minerals (but no vitamin D) One study involving 1298 pregnant women was included in this comparison. We assessed this study as having a low risk of bias in all domains. Pre-eclampsia was not reported. The evidence is very uncertain about the effect of supplementation with vitamin D, calcium, and other vitamins and minerals during pregnancy compared to no vitamin D on gestational diabetes (RR 0.42, 95% CI 0.10 to 1.73; very low-certainty evidence), maternal adverse events (hypercalcaemia no events and hypercalciuria RR 0.25, 95% CI 0.02 to 3.97; very low-certainty evidence), preterm birth (RR 1.04, 95% CI 0.68 to 1.59; low-certainty evidence), or low birthweight (RR 1.12, 95% CI 0.82 to 1.51; low-certainty evidence).

AUTHORS' CONCLUSIONS

This updated review using the trustworthy assessment tool removed 21 studies from the previous update and added one new study for a total of 10 included studies. In this setting, supplementation with vitamin D alone compared to no intervention or a placebo resulted in very uncertain evidence on pre-eclampsia, gestational diabetes, preterm birth, or nephritic syndrome. It may reduce the risk of severe postpartum haemorrhage; however, only one study reported this outcome. It may also reduce the risk of low birthweight; however, the upper CI suggests that an increase in risk cannot be ruled out. Supplementation with vitamin D and calcium versus placebo or no intervention resulted in very uncertain evidence on preterm birth and low birthweight. Pre-eclampsia, gestational diabetes, and maternal adverse events were not reported in the only study included in this comparison. Supplementation with vitamin D + calcium + other vitamins and minerals versus calcium + other vitamins and minerals (but no vitamin D) resulted in very uncertain evidence on gestational diabetes and maternal adverse events (hypercalciuria) and uncertain evidence on preterm birth and low birthweight. Pre-eclampsia was not reported in the only study included in this comparison. All findings warrant further research. Additional rigorous, high-quality, and larger randomised trials are required to evaluate the effects of vitamin D supplementation in pregnancy, particularly in relation to the risk of maternal adverse events.

Renal calcium and magnesium handling during pregnancy: modeling and analysis

Pregnancy is associated with elevated demand of most nutrients, with many trace elements and minerals critical for the development of fetus. In particular, calcium (Ca2+) and magnesium (Mg2+) are essential for cellular function, and their deficiency can lead to impaired fetal growth. A key contributor to the homeostasis of these ions is the kidney, which in a pregnant rat undergoes major changes in morphology, hemodynamics, and molecular structure. The goal of this study is to unravel the functional implications of these pregnancy-induced changes in renal handling of Ca2+ and Mg2+, two cations that are essential in a healthy pregnancy. To achieve that goal, we developed computational models of electrolyte and water transport along the nephrons of a rat in mid and late pregnancy. Model simulations reveal a substantial increase in the reabsorption of Mg2+ along the proximal tubules and thick ascending limbs. In contrast, the reabsorption of Ca2+ is increased in the proximal tubules but decreased in the thick ascending limbs, due to the lower transepithelial concentration gradient of Ca2+ along the latter. Despite the enhanced transport capacity, the marked increase in glomerular filtration rate results in elevated urinary excretions of Ca2+ and Mg2+ in pregnancy. Furthermore, we conducted simulations of hypocalcemia and hypomagnesemia. We found that hypocalcemia lowers Ca2+ excretion substantially more than Mg2+ excretion, with this effect being more pronounced in virgin rats than in pregnant ones. Conversely, hypomagnesemia reduces the excretion of Mg2+ and Ca2+ to more similar degrees. These differences can be explained by the greater sensitivity of the calcium-sensing receptor (CaSR) to Ca2+ compared with Mg2+.NEW & NOTEWORTHY A growing fetus' demands of minerals, notably calcium and magnesium, necessitate adaptations in pregnancy. In particular, the kidney undergoes major changes in morphology, hemodynamics, and molecular structure. This computational modeling study provides insights into how these pregnancy-induced renal adaptation impact calcium and magnesium transport along different nephron segments. Model simulations indicate that, despite the enhanced transport capacity, the marked increase in glomerular filtration rate results in elevated urinary excretions of calcium and magnesium in pregnancy.

Prenatal but not continued postpartum vitamin D supplementation reduces maternal bone resorption as measured by C-terminal telopeptide of type 1 collagen without effects on other biomarkers of bone metabolism

Vitamin D is a key regulator of bone mineral homeostasis and may modulate maternal bone health during pregnancy and postpartum. Using previously-collected data from the Maternal Vitamin D for Infant Growth (MDIG) trial in Dhaka, Bangladesh, we aimed to investigate the effects of prenatal and postpartum vitamin D3 supplementation on circulating biomarkers of bone formation and resorption at delivery and 6 months postpartum. MDIG trial participants were randomized to receive a prenatal;postpartum regimen of placebo or vitamin D3 (IU/week) as either 0;0 (Group A), 4200;0 (B), 16,800;0 (C), 28,000;0 (D) or 28,000;28,000 (E) from 17 to 24 weeks' gestation to 6 months postpartum. As this sub-study was not pre-planned, the study sample included MDIG participants who had data for at least 1 biomarker of interest at delivery or 6 months postpartum, with a corresponding baseline measurement (n = 690; 53 % of 1300 enrolled trial participants). Biomarkers related to bone turnover were measured in maternal venous blood samples collected at enrolment, delivery, and 6 months postpartum: osteoprotegerin (OPG), osteocalcin (OC), receptor activator nuclear factor kappa-B ligand (RANKL), fibroblast growth factor 23 (FGF23), procollagen type 1 N-terminal propeptide, (P1NP) and carboxy terminal telopeptide of type 1 collagen (CTx). Supplementation effects were expressed as percent differences between each vitamin D group and placebo with 95 % confidence intervals (95 % CI). Of 690 participants, 64 % had 25-hydroxyvitamin D concentrations (25OHD) <30 nmol/L and 94 % had 25OHD < 50 nmol/L at trial enrolment. At delivery, mean CTx concentrations were 27 % lower in group E versus placebo (95 % CI: -38, -13; P < 0.001), adjusting for enrolment concentrations. However, at 6 months postpartum, CTx concentrations were not statistically different in group E versus placebo (14 %; 95 % CI: -5.3, 37; P = 0.168), adjusting for delivery CTx concentrations. Effects on other biomarkers at delivery or postpartum were not statistically significant. In conclusion, prenatal high-dose vitamin D supplementation reduced bone resorption during pregnancy, albeit by only one biomarker, and without evidence of a sustained effect in the postpartum period. However, further evidence is needed to substantiate potential maternal bone health benefits of vitamin D in the postpartum period.

Lumbar spine bone mineral density in women breastfeeding for a period of 4 to 6 months: systematic review and meta-analysis

BACKGROUND

During the breastfeeding period, important transient changes in calcium homeostasis are verified in the maternal skeleton, to meet the demand for calcium for breastmilk production. The literature is inconclusive regarding the causes and percentages of involvement of bone densitometry resulting from exclusive breastfeeding (4 to 6 months).

METHODS

This article aims to systematically review the literature, to determine the occurrence, intensity, and factors involved in alterations in maternal bone mineral density (BMD), during a period of 4 to 6 months of exclusive breastfeeding. The search descriptors "woman", "breastfeeding", "human milk", and "bone mineral density" were used in the electronic databases of the Virtual Health Library, Scielo (Scientific Electronic Library Online), CAPES Periodicals Portal, LILACS, Embase, PubMed/Medline, Cochrane, Scopus, and Web of Science in June 2023. Inclusion criteria for breastfeedingmothers were; aged to 40 years, primigravida, exclusively breastfeeding, with BMD assessments using dual-energy X-ray absorptiometry (DXA), with values expressed at baseline and from 4 to 6 months postpartum. The Jadad scale, Newcastle-Ottawa Scale, and Oxford Centre for Evidence-based Medicine - levels of evidence were adopted to assess the quality of the studies. For the meta-analytical study, statistical calculations were performed.

RESULTS

Initially, 381 articles were found using the search strategy and 26 were read in full. After risk of bias analysis, 16 articles remained in the systematic review and four were included in the meta-analysis. The studies showed a reduction in bone mass in the lumbar spine in the first months postpartum (4 - 6 months), when compared with a longer period of breastfeeding (12-18 months). The breastfeeding group presented a greater impact in the meta-analysis than the control group (non-breastfeeding, pregnant, or immediate postpartum), with a reduction in BMD in the lumbar spine of -0.18 g/cm2 (-0.36, -0.01 g/cm2); 95% Confidence Interval, on a scale from 0 to 10.

CONCLUSIONS

Our results demonstrated a transitory reduction in bone densitometry of the lumbar spine during exclusive breastfeeding for 4 to 6 months, which was gradually restored later in the postpartum period. More prospective studies are needed to better understand the topic.

TRIAL REGISTRATION

PROSPERO platform (nº CRD42021279199), November 12th, 2021.

Assessment of energy and nutrient intake of sri lankan mothers with prior gestational diabetes mellitus at 6-week postpartum: A community-based study

Background

Gestational diabetes mellitus (GDM) is one of the leading causes for the future diabetes. Diet modification is an imperative part in attenuating this progression.

Objectives

This study assessed energy and nutrient intakes of Sri Lankan mothers at 6 weeks after delivery, with the aim of developing specific dietary guidelines for postpartum mothers with GDM.

Materials and Methods

A community-based, descriptive cross-sectional survey was conducted as a part of a quasi-experimental study. Nutrient and energy intakes were assessed among 100 mothers using 24-h dietary recall and a validated food frequency questionnaire. Energy and nutrient intakes were analyzed using NutriSurvey 2007 (EBISpro, Germany) which was modified for native food recipes and food composition tables for Sri Lanka.

Results

The mean ± standard deviation intakes of total calories, carbohydrate, protein, and fat were 2817 ± 984 kcal, 445 ± 186 g, 95 ± 39 g, and 87 ± 58 g, respectively. The total calorie intake was significantly higher when compared to recommended levels based on the body mass index in both normal weight (3033 ± 1122 vs. 2300 kcal/d; P < 0.00) and overweight or obese (2759 ± 944 vs. 1800 kcal/d; P < 0.00) postpartum women. In the obese group, daily carbohydrate, fat, and protein intakes were significantly higher than the recommended values (P < 0.00). Folic acid intake was lower in both normal (23.7 vs. 400; P < 0.001) and obese or overweight (63 vs. 400; P < 0.001) groups.

Conclusion

The study indicated that in majority of the mothers with GDM, the daily calorie and carbohydrate intakes were higher than the recommended. The findings suggest the need for developing a scientifically feasible and culturally acceptable dietary modification program. All macronutrients were taken more than the recommended amounts, especially in the overweight/obese group.

Dietary supplements and vascular function in hypertensive disorders of pregnancy

Hypertensive disorders of pregnancy are complications that can lead to maternal and infant mortality and morbidity. Hypertensive disorders of pregnancy are generally defined as hypertension and may be accompanied by other end organ damages including proteinuria, maternal organ disturbances including renal insufficiency, neurological complications, thrombocytopenia, impaired liver function, or uteroplacental dysfunction such as fetal growth restriction and stillbirth. Although the causes of these hypertensive disorders of pregnancy are multifactorial and elusive, they seem to share some common vascular-related mechanisms, including diseased spiral arteries, placental ischemia, and endothelial dysfunction. Recently, preeclampsia is being considered as a vascular disorder. Unfortunately, due to the complex etiology of preeclampsia and safety concerns on drug usage during pregnancy, there is still no effective pharmacological treatments available for preeclampsia yet. An emerging area of interest in this research field is the potential beneficial effects of dietary intervention on reducing the risk of preeclampsia. Recent studies have been focused on the association between deficiencies or excesses of some nutrients and complications during pregnancy, fetal growth and development, and later risk of cardiovascular and metabolic diseases in the offspring. In this review, we discuss the involvement of placental vascular dysfunction in preeclampsia. We summarize the current understanding of the association between abnormal placentation and preeclampsia in a vascular perspective. Finally, we evaluate several studied dietary supplementations to prevent and reduce the risk of preeclampsia, targeting placental vascular development and function, leading to improved pregnancy and postnatal outcomes.

Dietary Diversity, Micronutrient Adequacy and Bone Status during Pregnancy: A Study in Urban China from 2019 to 2020

Diet quality during reproduction is crucial to maternal and infant health. However, the association between dietary diversity and bone health of pregnant women remains unclear. We aimed to evaluate the dietary quality of Chinese urban gravidas using the dietary diversity score (DDS), and to explore the relationship of the DDS with micronutrient adequacy and bone health. In this cross-sectional study, we analyzed data from 775 pregnant women aged 18 years or older in urban China. Dietary diversity was assessed using the Minimum Dietary Diversity for Women (MDD-W) indicator. A 24-h dietary recall was used to collect diet data and to calculate the MDD-W and the nutrient intake. Bone health was measured using quantitative ultrasound and assessed by the speed of sound (SOS). Pearson's correlation coefficients between the DDS and the nutrient adequacy ratio (NAR) were calculated. A multivariable linear regression model was used to estimate the effect size of the DDS on the SOS. The mean DDS was 6.61 ± 1.53 points and 91.0% of participants reported the consumption of five or more food groups. Women in the diverse diet subgroup (DDS ≥ 7 points) were more likely to consume all kinds of food except starchy staples and had higher NARs. Pearson's correlation coefficients between the DDS and the NAR ranged from 0.161 to 0.484. For participants in the second trimester, those with a diverse diet had a higher SOS. A multivariable linear regression analysis showed that the DDS was positively and significantly associated with the SOS (β = 17.18, 95% CI = 5.97-28.39, p = 0.003), but this was not the case for women in the first and third trimesters. Urban Chinese women had good dietary diversity during pregnancy. A higher dietary diversity was associated with a higher NAR. From the point of view of bone, a diverse diet was positively correlated with better bone status, suggesting the importance of improving diet diversity for pregnant women, especially from mid-pregnancy.

Individualized high dairy protein + walking program supports bone health in pregnancy: a randomized controlled trial

BACKGROUND

Pregnancy induces bone mineral mobilization, which may be further compromised if diet and physical activity are suboptimal.

OBJECTIVES

We aimed to determine the effects of a Nutrition + Exercise intervention during pregnancy on maternal calciotropic and bone biomarker profiles throughout pregnancy and the postpartum.

METHODS

In the Be Healthy in Pregnancy (BHIP) randomized controlled trial, 203 of 225 participants who consented to the bone health substudy were, randomly assigned at 12-17 weeks gestation to receive either usual care (control) or a structured and monitored Nutrition + Exercise plan (intervention) providing an individualized high dairy protein diet and a walking program throughout pregnancy. Maternal serum total procollagen type 1 N-terminal propeptide (P1NP; bone formation), C-terminal telopeptide of type I collagen (CTX; bone resorption), and insulin-like growth factor-1 (IGF-1) were measured by ELISA, and vitamin D metabolites by ultra-performance LC tandem MS at early and late pregnancy, 6 mo postpartum, and in cord blood.

RESULTS

In 187 participants completing all measures, significantly higher intakes were observed in the intervention than in the control group for total protein (P < 0.0001), protein intake from dairy foods (P < 0.0001), and calcium (P < 0.0001), whereas vitamin D intake was similar between treatment groups in both the second and third trimesters. The intervention group had significantly lower serum CTX at end of pregnancy (mean ± SD: 0.78 ± 0.31 ng/mL; n = 91 compared with 0.89 ± 0.33 ng/mL; n = 96, P = 0.034) and in cord serum (0.58 ± 0.13 ng/mL; n = 31 compared with 0.69 ± 0.18 ng/mL; n = 22, P < 0.025). Serum concentrations of P1NP rose significantly (P < 0.02) from early pregnancy to 6 mo postpartum for the intervention group only. Serum 25-hydroxyvitamin D status was >50 nmol/L for 97% of all participants.

CONCLUSIONS

Higher maternal dietary protein and calcium intakes than usual care in concert with normal vitamin D status minimized bone resorption and maintained bone formation and may protect bone health during pregnancy.This trial was registered at clinicaltrials.gov as NCT01689961.

Calcium supplementation for the prevention of hypertensive disorders of pregnancy: current evidence and programmatic considerations

Most low- and middle-income countries present suboptimal intakes of calcium during pregnancy and high rates of mortality due to maternal hypertensive disorders. Calcium supplementation during pregnancy is known to reduce the risk of these disorders and associated complications, including preeclampsia, maternal morbidity, and preterm birth, and is, therefore, a recommended intervention for pregnant women in populations with low dietary calcium intake (e.g., where ≥25% of individuals in the population have intakes less than 800 mg calcium/day). However, this intervention is not widely implemented in part due to cost and logistical issues related to the large dose and burdensome dosing schedule (three to four 500-mg doses/day). WHO recommends 1.5-2 g/day but limited evidence suggests that less than 1 g/day may be sufficient and ongoing trials with low-dose calcium supplementation (500 mg/day) may point a path toward simplifying supplementation regimens. Calcium carbonate is likely to be the most cost-effective choice, and it is not necessary to counsel women to take calcium supplements separately from iron-containing supplements. In populations at highest risk for preeclampsia, a combination of calcium supplementation and food-based approaches, such as food fortification with calcium, may be required to improve calcium intakes before pregnancy and in early gestation.

Calcium supplementation during pregnancy and maternal and offspring bone health: a systematic review and meta-analysis

Insufficient calcium intake during pregnancy may lead to maternal bone resorption and lower bone density of offspring. We evaluated the impact of supplementary calcium with or without vitamin D during pregnancy on maternal and offspring bone mineral density (BMD) and teeth firmness of the offspring. Randomized controlled trials (RCTs) were searched systematically in 11 databases. Two researchers independently screened the titles and abstracts of 3555 records and the full texts of 31 records to examine eligibility. The search yielded seven RCTs (11 reports, n = 1566).  No advantage of calcium supplementation was found on maternal BMD after delivery or during breastfeeding, or on offspring BMD, even when dietary calcium intake was low. The results were neither modified by the dose of calcium nor concomitant vitamin D administration. A suspicion of some long-term harm of the intervention on maternal BMD and growth of female offspring was raised based on the data. One study suggested some benefit of high-dose calcium supplementation on offspring teeth firmness at 12 years old. A low number of the studies and abundant missing data reduced the quality of the findings. The impact of calcium supplementation on maternal and offspring bone health was deemed unknown because of inconclusive research results.

Perspectives on the systematic review for the 2020 Dietary Reference Intakes for Koreans for calcium

An accurate assessment of the recommended calcium (Ca) intake may contribute to reducing the risk of fractures and chronic diseases, ultimately improving quality of life. This review was performed to summarize key findings of Ca studies, investigate the effect of Ca intake on health outcomes, and determine the adequacy of evidence to revise the 2015 Dietary Reference Intakes for Koreans (KDRIs) for Ca in 2020. Databases were searched for intervention studies that assessed health outcomes by providing Ca in diets or as supplements. The framework of the systematic review comprised conducting literature searches, data extraction, quality assessment of the literature, and summarizing key findings relevant to set the Estimated Average Requirement (EAR) and Tolerable Upper Intake Level (UL) for Ca for the 2020 KDRI. The final search was performed in June 2019. A total of 13,309 studies were identified through databases and manual search. Sixtyfive studies were included in the final quality assessment and were summarized according to health indicators. As bone health was used as an indicator of the EAR for Ca, literature reports on bone health were further categorized by the life-cycle stage of the participants. This systematic review did not find new evidence that could be applied to the general Korean adult population, including postmenopausal women, for defining a new EAR for Ca in the 2020 KDRIs. Evidence in most of the reviewed literature was considered weak; however, some evidence was found that could improve the criteria on how the EAR for Ca was determined in children and adolescents. A review of the literature for the 2020 KDRIs for Ca did not find strong evidence in order to change the recommended values of the 2015 KDRIs. More clinical interventions are required among Koreans to strengthen the body of evidence to warrant the revision of the KDRIs.

A "secret shopper" survey of community pharmacist prenatal vitamin recommendations

BACKGROUND

As pharmacists assume a larger role in prenatal and preconception care, providing an evidence-based recommendation for a prenatal vitamin is essential.

OBJECTIVES

To identify the prenatal vitamins that community pharmacists are recommending to patients and compare the contents with national and international standards. The secondary objectives were to compare responses between the type of pharmacy (chain, grocery, or independent) and region of Michigan.

METHODS

A female student pharmacist posing as a patient anonymously interviewed 60 community pharmacists distributed across 5 different regions of Michigan through telephone to determine prenatal vitamin recommendations for preconception use. The regions of Michigan were included to determine if sociodemographic factors were associated with varying responses or recommendations.

RESULTS

Of the pharmacists interviewed, 97% recommended a prenatal vitamin, with 81% recommending an over-the-counter (OTC) prenatal vitamin. Only 33% of the pharmacists provided a specific brand name. Folic acid was the most common ingredient that the pharmacists identified to look for in a prenatal vitamin, followed by docosahexaenoic acid and iron. No difference was detected in the pharmacist responses across type of pharmacy (chain, grocery store chain, or independent). A difference was found between regions of Michigan and recommendations for a specific prenatal vitamin brand (P = 0.017).

CONCLUSION

Most of the community pharmacists recommended an OTC prenatal vitamin with an adequate amount of folic acid. Considering the broad range of prenatal vitamins on the market, a clear recommendation from a pharmacist about a specific prenatal vitamin that contains adequate nutrients is paramount. Expanding the knowledge and understanding of key prenatal vitamin ingredients and availability may strengthen future recommendations.

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.

Pregnancy-Related Change in pQCT and Bone Biochemistry in a Population With a Habitually Low Calcium Intake

In pregnancy, changes in maternal calcium (Ca) economy occur to satisfy fetal Ca demand. It is unclear whether maternal mineral reserves facilitate these requirements and no data exist from sub-Saharan Africa. The aim was to determine skeletal changes with peripheral quantitative computed tomography (pQCT) and bone biochemistry between early second and third trimesters. Pregnant rural Gambians aged 18 to 45 years (n = 467) participating in a trial of antenatal nutritional supplements (ISRCTN49285450) had pQCT scans and blood collections at mean (SD) 14 (3) and 31 (1) weeks' gestation. Outcomes were pQCT: radius/tibia 4% total volumetric bone mineral density (vBMD), trabecular vBMD, total cross-sectional area (CSA), 33%/38% radius/tibia cortical vBMD, bone mineral content (BMC), total CSA; biochemistry: collagen type 1 cross-linked β-C-telopeptide (β-CTX), type 1 procollagen N-terminal (P1NP), parathyroid hormone (PTH), and 1,25(OH)₂ D. Independent t tests tested whether pooled or within-group changes differed from 0. Multiple regression was performed adjusting for age. Data for change are expressed as mean (confidence interval [CI] 2.5, 97.5%). Radius trabecular vBMD, cortical vBMD, and BMC increased by 1.15 (0.55, 1.75)%, 0.41 (0.24, 0.58)%, and 0.47 (0.25, 0.69)%. Tibia total and trabecular vBMD increased by 0.34 (0.15, 0.54)% and 0.46 (0.17, 0.74)%, while tibia cortical vBMD, BMC, and cortical CSA increased by 0.35 (0.26, 0.44)%, 0.55 (0.41, 0.68)% and 0.20 (0.09, 0.31)%, respectively. CTX, PTH, and 1,25(OH)₂ D increased by 23.0 (15.09, 29.29)%, 13.2 (8.44, 19.34)%, and 21.0 (17.67, 24.29)%, while P1NP decreased by 32.4 (-37.19, -28.17)%. No evidence of mobilization was observed in the peripheral skeleton. Resorption, although higher in late versus early gestation, was lower throughout pregnancy compared with non-pregnant non-lactating (NPNL) in the same community. Formation was lower in late pregnancy than in early, and below NPNL levels. This suggests a shift in the ratio of resorption to formation. Despite some evidence of change in bone metabolism, in this population, with habitually low Ca intakes, the peripheral skeleton was not mobilized as a Ca source for the fetus. © 2021 crown copyright . Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). The article published with the permission of the Controller of HMSO and the Queen's Printer of Scotland..

Reduction in Bone Loss from 5 to 20 Weeks Postpartum in Adolescents Supplemented with Calcium Plus Vitamin D during Pregnancy Is Not Sustained at 1 Year Postpartum: Follow-up Study of a Randomized Controlled Trial

BACKGROUND

Calcium plus vitamin D supplementation of pregnant Brazilian adolescents with habitually low calcium intake (∼600 mg/d) reduced bone loss during the first 20 wk postpartum.

OBJECTIVE

We investigated maternal bone mass changes during the first year postpartum as a follow-up of the clinical trial.

METHODS

Pregnant adolescents (14-19 y) received calcium (600 mg/d) plus cholecalciferol (200 IU/d) supplementation (n = 30) or placebo (n = 26) from 26 wk of gestation until parturition. Bone area and bone mineral content and bone mineral density (BMD) at total body, lumbar spine, and hip (total and femoral neck) were assessed by DXA at 3 time points postpartum (5 wk, 20 wk, and 56 wk). Intervention group, time postpartum, and group × time interaction effects were tested by repeated-measures mixed-effects models adjusting for calcium intake, return of menses, breastfeeding practices, and body weight.

RESULTS

Time (P < 0.05) but not group affected several absolute bone measurements. There was a group × time interaction for femoral neck BMD (P = 0.045). Mean ± SE values (g/cm2) at 5 wk, 20 wk, and 56 wk were, respectively, 1.025 ± 0.026, 0.980 ± 0.026, and 1.022 ± 0.027 for the placebo group and 1.057 ± 0.025, 1.030 ± 0.024, and 1.055 ± 0.025 for the supplemented group. An interaction also was observed for percentage change in femoral neck BMD relative to 5 wk (P = 0.049), with a more pronounced decrease in the placebo group (-4.58 ± 0.42%) than in the supplemented group (-3.15% ± 0.42%) at 20 wk (P = 0.019), and no difference between groups at 56 wk (-0.44% ± 0.71% in the placebo and -0.76% ± 0.62% in the supplemented group; P = 0.65).

CONCLUSIONS

Calcium plus vitamin D supplementation of the adolescent mothers reduces the magnitude of bone loss at the femoral neck from 5 to 20 wk postpartum without an effect on bone changes after 1 y postpartum, indicating that there is no sustained effect of the supplement tested.

Pregnancy-Related Bone Mineral and Microarchitecture Changes in Women Aged 30 to 45 Years

At birth, the neonatal skeleton contains 20 to 30 g calcium (Ca). It is hypothesized maternal bone mineral may be mobilized to support fetal skeletal development, although evidence of pregnancy-induced mineral mobilization is limited. We recruited healthy pregnant (n = 53) and non-pregnant non-lactating (NPNL; n = 37) women aged 30 to 45 years (mean age 35.4 ± 3.8 years) and obtained peripheral quantitative computed tomography (pQCT) and high-resolution pQCT (HR-pQCT) scans from the tibia and radius at 14 to 16 and 34 to 36 weeks of pregnancy, with a similar scan interval for NPNL. Multiple linear regression models were used to assess group differences in change between baseline and follow-up; differences are expressed as standard deviation scores (SDS) ± SEM. Decreases in volumetric bone mineral density (vBMD) outcomes were found in both groups; however, pregnancy-related decreases for pQCT total and trabecular vBMD were -0.65 ± 0.22 SDS and -0.50 ± 0.23 SDS greater (p < .05). HR-pQCT total and cortical vBMD decreased compared with NPNL by -0.49 ± 0.24 SDS and -0.67 ± 0.23 SDS, respectively; trabecular vBMD decreased in both groups to a similar magnitude. Pregnancy-related changes in bone microarchitecture significantly exceeded NPNL change for trabecular number (0.47 ± 0.23 SDS), trabecular separation (-0.54 ± 0.24 SDS), cortical thickness (-1.01 ± 0.21 SDS), and cortical perimeter (0.78 ± 0.23 SDS). At the proximal radius, cortical vBMD and endosteal circumference increased by 0.50 ± 0.23 SDS and 0.46 ± 0.23 SDS, respectively, compared with NPNL, whereas cortical thickness decreased -0.50 ± 0.22 SDS. Pregnancy-related decreases in total and compartment-specific vBMD exceed age-related change at the distal tibia. Changes at the radius were only evident with pQCT at the cortical-rich proximal site and suggest endosteal resorption. Although the magnitude of these pregnancy-related changes in the appendicular skeleton are small, if they reflect global changes across the skeleton at large, they may contribute substantially to the Ca requirements of the fetus. © 2020 Crown copyright. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.

Pregnancy and lactation, a challenge for the skeleton

In this review we discuss skeletal adaptations to the demanding situation of pregnancy and lactation. Calcium demands are increased during pregnancy and lactation, and this is effectuated by a complex series of hormonal changes. The changes in bone structure at the tissue and whole bone level observed during pregnancy and lactation appear to largely recover over time. The magnitude of the changes observed during lactation may relate to the volume and duration of breastfeeding and return to regular menses. Studies examining long-term consequences of pregnancy and lactation suggest that there are small, site-specific benefits to bone density and that bone geometry may also be affected. Pregnancy- and lactation-induced osteoporosis (PLO) is a rare disease for which the pathophysiological mechanism is as yet incompletely known; here, we discuss and speculate on the possible roles of genetics, oxytocin, sympathetic tone and bone marrow fat. Finally, we discuss fracture healing during pregnancy and lactation and the effects of estrogen on this process.

Calcium Intake and Health

There are striking inequities in calcium intake between rich and poor populations. Appropriate calcium intake has shown many health benefits, such as reduction of hypertensive disorders of pregnancy, lower blood pressure particularly among young people, prevention of osteoporosis and colorectal adenomas, lower cholesterol values, and lower blood pressure in the progeny of mothers taking sufficient calcium during pregnancy. Studies have refuted some calcium supplementation side effects like damage to the iron status, formation of renal stones and myocardial infarction in older people. Attention should be given to bone resorption in post-partum women after calcium supplementation withdrawal. Mechanisms linking low calcium intake and blood pressure are mediated by parathyroid hormone raise that increases intracellular calcium in vascular smooth muscle cells leading to vasoconstriction. At the population level, an increase of around 400-500 mg/day could reduce the differences in calcium intake between high- and middle-low-income countries. The fortification of food and water seems a possible strategy to reach this goal.