Bone loss in adolescent and adult pregnant women

Adolescent Nutrition-Developing a Research Agenda for the Second Window of Opportunity in Indonesia

BACKGROUND

Recently, adolescence has been identified as a second window of opportunity for the correction of nutritional inadequacies. However, there is a lack of knowledge on evidence-based integrated nutrition strategies for adolescents in Indonesia.

OBJECTIVE

To provide a research agenda and the prioritization of research actions to tackle outstanding knowledge gaps on adolescent nutrition in Indonesia.

METHODS

A preliminary set of research topics was listed based on a desk study of the academic literature and policy documents. Second, a stakeholder meeting was held to further identify and discuss research topics related to adolescent nutrition in Indonesia. Third, an online survey was conducted in which respondents were asked to indicate priority research themes for the next 3 to 5 years and to rank a total of 23 research questions.

RESULTS

Most (52%) of the respondents who returned the survey (n = 27) prioritize research on implementation and program evaluation, while 30% prefer descriptive and explanatory research, and 19% place priority with intervention and discovery research. However, when we followed up with specific topics for each of these broad research areas, a more nuanced picture emerged, with intervention and discovery research taking a more prominent standing.

CONCLUSIONS

In order to support the design, implementation, and effectiveness of integrated nutrition programs for Indonesian adolescents, in-depth studies should question the best intervention strategies, modes of delivery, and long-term outcomes, while nationwide and disaggregated data should investigate associations and trends over time and identify vulnerable groups.

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

Background

Low calcium intake during pregnancy may cause maternal skeletal calcium mobilization to meet fetal needs. The Recommended Dietary Allowance (RDA) for calcium in nonpregnant, pregnant, or lactating women aged 19-50 y is 1000 mg/d; most women in the United States report consuming 60-80% of the calcium RDA. An insufficient calcium intake could increase maternal bone loss during pregnancy and reduce bone recovery postpartum.

Objectives

The aim of this study was to determine the effect of maternal calcium supplementation on peripheral cortical and trabecular bone loss during pregnancy and bone gain postpartum.

Methods

A total of 64 women were enrolled in the study at 16 wk of gestation and randomly assigned to receive 1000 mg Ca/d or placebo for the remainder of the pregnancy. Measurements were performed at 16, 26, and 36 wk of pregnancy and at 4 and 12 mo postpartum for serum 25-hydroxyvitamin D and markers of bone turnover. Trabecular and cortical bone mineral density (BMD) and content were assessed at the tibia and radius by peripheral quantitative computed tomography.

Results

Mean ± SD daily calcium intake at baseline was 733 ± 350 mg; only 25% of the women met the RDA. Thirty women (47% of those enrolled) remained in the study at 12 mo postpartum. After controlling for baseline bone value, serum 25-hydroxyvitamin D concentrations, length of breastfeeding, and body mass index, the calcium group had significantly greater increases in radial total BMD (P = 0.02) and tibial cortical BMD (P = 0.03) at 12 mo postpartum than the placebo group. Trabecular and total BMD at the tibia trended toward higher values (P < 0.06) in the calcium group than in the placebo group in the same models.

Conclusions

These data show that supplemental calcium provided during pregnancy may improve bone recovery postpartum in women consuming a typical US diet. A larger study is warranted to solidify the conclusions. This trial was registered at clinicaltrials.gov as NCT01145573.

Maternal type 1collagen N-terminal telopeptide levels in severe hyperemesis gravidarum

Background

Nausea and vomiting occur 50–90% during the first trimester of pregnancy. However, patients with hyperemesis gravidarum (HG) may be hospitalized at an incidence rate of 0.8–2% before the 20th week of gestational age. The symptoms generally start during the 5–6th gestational weeks, reaching the highest degree during the 9th week, and decline after the 16–20th weeks of gestation. Clinical findings are proportional to the severity of the disease and severe HG is characterized with dehydration, electrolyte imbalance, and nutritional deficiency as a result of vomiting.

Methods

The study population consisted of two groups of pregnant volunteers at 5–12 weeks of gestation: a severe HG group and a control group. The HG severity was scored using the Pregnancy-Unique Quantification of Emesis (and nausea) (PUQE).The serum levels of the maternal Ca, parathyroid hormone (PTH), Na, K, blood urea nitrogen(BUN), creatinine, vitamin D(25OHD3), and the maternal urine NTx levels were compared between the groups.

Results

In total, 40 volunteers were enrolled in this study: 20 healthy pregnant volunteers and 20 with severe HG. There were no statistically significant differences between the maternal characteristics. The first trimester weight loss of ≥5 kg was significantly higher in the severe HG group (p < 0.001), while the control group had a significantly higher sunlight exposure ratio than the severe HG group (p = 0.021). The urine NTx levels were significantly higher in the severe HG group (39.22 ± 11.68NTx/Cre) than in the control group(32.89 ± 8.33NTx/Cre) (p = 0.028).The serum Ca, PTH, Na, K, BUN, and creatinine levels were similar between the groups (p = 0.738, p = 0.886, p = 0.841, p = 0.957, p = 0.892, and p = 0.824, respectively). In the severe HG group, the serum 25OHD₃ levels were significantly lower than in the control group (p < 0.001).

Conclusions

The data from this study indicated that severe HG is associated with increased urine NTx levels. However, large-scale studies are required to understand the clinical significance of this finding, as well as the long-term consequences of elevated urine NTx levels and the underlying mechanisms.

Trial registration

NCT02862496 Date of registration: 21/07/2016.

Using stable isotope tracers to study bone metabolism in children

Skeletal mineralization is initiated in utero and continues throughout childhood and adolescence. During these key periods of the life cycle, calcium retention must increase significantly to provide sufficient mineral for bone deposition and skeletal growth. Stable calcium isotopes have served as a fundamental tool to non-invasively characterize the dynamic changes in calcium physiology that occur from infancy through adolescence. These approaches have helped define the dynamics of calcium absorption and utilization in healthy children and in children with chronic diseases. As data in this area have accumulated, new areas of emphasis are beginning to characterize the determinants of variability in mineral retention, the genetic determinants of bone turnover and calcium flux and the impact of the gut microbiome on whole body and niche specific calcium dynamics. Advances in these areas will help define calcium utilization in paediatric populations and provide information that may be useful in maximizing bone acquisition across this critical phase of the life cycle.

Effect of Gestational Weight Gain and Prepregnancy Body Mass Index in Adolescent Mothers on Weight and Body Mass Index of Adolescent Offspring

PURPOSE

The purpose of the study was to examine the association of the gestational weight gain and prepregnancy body mass index (BMI) of low-income adolescent mothers with the risk of their children being overweight and/or obese in late adolescence.

METHODS

Study subjects were low-income, primiparous adolescents (n = 360) who self-identified as black and participated in the New Mothers Study in Memphis, Tennessee, and their children. Gestational weight gain was examined as a continuous variable and also categorized into overgain, recommended gain, and undergain following the 2009 Institute of Medicine guidelines. The effects of maternal prepregnancy BMI percentiles and calculated BMI were also considered. Multivariable logistic and linear regression models were used. The main outcome measures were offspring overweight, obesity, and BMI.

RESULTS

Thirty-nine percent of offspring were overweight or obese. Higher maternal gestational weight gain increased the risk for offspring overweight and obesity. There was an interaction between gestational weight gain and prepregnancy BMI: offspring of mothers with a BMI percentile ≤76 were at greater risk of obesity with higher maternal weight gain. If mothers with a BMI percentile between the 29th and 83rd percentiles overgained, offspring were at greater risk for overweight. Using calculated BMIs, if a mother's BMI was ≤26 kg/m², offspring risk for obesity was greater with higher gestational weight gain.

CONCLUSIONS

High gestational weight gain had a larger effect on offspring overweight and obesity if maternal prepregnancy BMI percentile was ≤76. The gestational weight gain of primiparous adolescents who self-identified as black had an effect on offspring weight.

Reduced maternal calcium intake through nutrition and supplementation is associated with adverse conditions for both the women and their infants in a Chinese population

Effective nutritional guidelines for pregnant women in China are lacking. The aim of this study was to investigate the effect of dietary nutrition on the health condition of pregnant women and infants in China.In total, 331 pregnant women who had prenatal examinations were included in this study. Data, including dietary nutrition questionnaires, the weight, height, age, and health condition of the pregnant women as well as the health condition of the infants, were recorded.The average intake of milk, poultry and meat, fish and prawns, eggs, and bean products were 297.28 ± 129.67 mL/day, 123.34 ± 52.04 g/day, 157.31 ± 70.04 g/day, 67.34 ± 45.28 g/day, and 1.21 ± 0.62 per day, respectively. Among the 331 pregnant women, the intake rates of supplemental calcium and VD were 86.7% and 69.8%, respectively. The intake of milk, bean products, and meats was obviously lower (all P < .05) in the pregnant women with systremma compared to those without it. In addition, the body weight before and after delivery was higher (all P < .05) in the pregnant women with systremma. The calcium intake of the pregnant women and the infants' BMD were remarkably lower in the infants with pillow baldness or a wider anterior fontanelle (P < .01) compared to those without the features.The intake of milk, poultry and meat, fish and prawns, eggs, and bean products by pregnant women should be monitored, and in particular, the proper intake of milk, bean products, and meats, as well as calcium supplements, might decrease the occurrence of systremma in pregnant women and reduce the rate pillow baldness and a wider anterior fontanelle in infants.

Association between delivery at an advanced maternal age and osteoporosis in elderly Korean women

Although several reproductive factors have been associated with low bone mineral density (BMD) in elderly women, few studies have evaluated the long-term effects of delivery at a high-risk maternal age on BMD. Using nationally representative survey data collected from 736 women aged 65 years or older, we evaluated the relationship between delivery during adolescence or at an age of 35 years or older and osteoporosis in elderly women. Data regarding demographic and socioeconomic characteristics, medical history, lifestyle risk factors, reproductive history, and history of osteoporosis and fracture were collected by administration of self-report questionnaires. Anthropometric data and BMD were measured in accordance with standardized guidelines. Independent determinants of BMD were identified by stepwise multiple linear regression analysis, and the resulting model was used to evaluate the risk of osteoporosis according to delivery during adolescence or at an advanced age. Of the 736 subjects, 426 (60.1 %) were found to have osteoporosis (T score ≤ -2.5), and 19.2 and 38.9 % reported delivery during adolescence and at an advanced age, respectively. The incidence of delivery during adolescence or at an advanced age was significantly higher in subjects with osteoporosis than in those without osteoporosis. After adjustment for covariates, multiple logistic regression analysis revealed that elderly women with a history of delivery at an advanced maternal age are at an increased (2.164-fold greater) risk of osteoporosis (95 % confidence interval 1.109-4.223) compared with elderly women without a history of delivery at an advanced age. However, a history of delivery during adolescence did not affect the risk.

Age at First Delivery and Osteoporosis Risk in Korean Postmenopausal Women: The 2008-2011 Korea National Health and Nutrition Examination Survey (KNHANES)

It has been reported in several studies that there may be a significant correlation between reproductive history and the risk of osteoporosis due to the effect of estrogen. Under this hypothesis, however, it is unclear whether the age at first delivery has any major influences on the risk of osteoporosis. Therefore, this study aimed to investigate the relationship between the age at first delivery and the risk of osteoporosis in Korean menopausal women. This study was performed using data from the 2008–2011 Korea National Health and Nutrition Examination Survey and included 2,530 Korean postmenopausal women. The diagnosis of osteoporosis was made using the World Health Organization T-score criteria (T-score ≤ -2.5, at the femoral neck or lumbar spine). Participants were categorized into 3 groups according to age at first delivery: ≤23, 24–29, and ≥30 years. Older age, lower body mass index, lower calcium intake, later menarche, and earlier menopause increased the risk of osteoporosis, whereas hormone therapy and oral contraceptive use were associated with a decreased risk of osteoporosis. Postmenopausal women whose first delivery occurred at age 24–29 years were shown to have a significantly increased risk of osteoporosis (odds ratio, 2.124; 95% confidence interval, 1.096–4.113; P = 0.026) compared to those who first gave birth after the age of 30 years. These findings suggest that postmenopausal women whose first delivery occurred in their mid to late 20s, a period during which bone mass slowly accumulates to the peak, are at an increased risk of osteoporosis.

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

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

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

Background

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

Methods

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

Results

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

Conclusions

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

Trial registration

ClinicalTrials.gov Identifier NCT00558623

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

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

Osteoprotegerin in pregnant adolescents differs by race and is related to infant birth weight z-score

Osteoprotegerin (OPG) is involved in the regulation of bone turnover, but little is known about this protein during pregnancy or among neonates. We undertook a prospective longitudinal study to identify relationships between OPG, markers of bone turnover and birth outcomes in 155 pregnant adolescents (13-18 years) and their newborns. Maternal blood samples were collected at mid-gestation and at delivery. Cord blood was obtained at delivery. Serum OPG, estradiol and markers of bone formation (osteocalcin) and resorption (N-telopeptide) were assessed in all samples. Placental OPG expression was assessed in placental tissue obtained at delivery. Bone markers and OPG increased significantly from mid-gestation (26.0 ± 3.4 weeks) to delivery (39.3 ± 2.6 weeks). Neonatal OPG was significantly lower, but bone turnover markers were significantly higher than maternal values at mid-gestation and at parturition (P < 0.001). African-American adolescents had higher concentrations of OPG than Caucasian adolescents at mid-gestation (P = 0.01) and delivery (P = 0.04). Gestational age and estradiol were also predictors of maternal OPG at mid-gestation and delivery. OPG concentrations in cord blood were correlated with maternal OPG concentrations and were negatively associated with infant birth weight z-score (P = 0.02) and ponderal index (P = 0.02). In conclusion, maternal OPG concentrations increased across gestation and were significantly higher than neonatal OPG concentrations. Maternal and neonatal OPG concentrations were not associated with markers of bone turnover or placental OPG expression, but neonatal OPG was inversely associated with neonatal anthropometric measures. Additional research is needed to identify roles of OPG during pregnancy.

Role of calcium during pregnancy: maternal and fetal needs

Although the demand for additional calcium during pregnancy is recognized, the dietary reference intake for calcium was lowered for pregnant women in 1997 to amounts recommended for nonpregnant women (1,000 mg/day), and recently (November 2010) the Institute of Medicine report upheld the 1997 recommendation. It has been frequently reported that women of childbearing age do not consume the dietary reference intake for calcium and that calcium intake in the United States varies among ethnic groups. Women who chronically consume suboptimal amounts of calcium (<500 mg/day) may be at risk for increased bone loss during pregnancy. Women who begin pregnancy with adequate intake may not need additional calcium, but women with suboptimal intakes (<500 mg) may need additional amounts to meet both maternal and fetal bone requirements. The objective of this review is to elucidate the changes in calcium metabolism that occur during pregnancy as well as the effect of maternal calcium intake on both maternal and fetal outcomes.

Serum 1,25-dihydroxyvitamin D and calcium intake affect rates of bone calcium deposition during pregnancy and the early postpartum period

BACKGROUND

Factors affecting bone calcium deposition across pregnancy and lactation are not well characterized.

OBJECTIVE

The impact of maternal age, calcium intake, race-ethnicity, and vitamin D status on the rate of bone calcium deposition (VO+) was assessed across pregnancy and lactation.

DESIGN

Stable calcium isotopes were given to 46 women at pre- or early pregnancy (trimester 1), late pregnancy (trimester 3), and 3-10 wk postpartum. Three cohorts were included: 23 adolescents from Baltimore (MD), aged 16.5 ± 1.4 y (mean ± SD; Baltimore cohort); 13 adults from California, aged 29.5 ± 2.6 y (California cohort); and 10 adults from Brazil, aged 30.4 ± 4.0 y (Brazil cohort). The total exchangeable calcium pool, VO+, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D [1,25(OH)₂D], parathyroid hormone, and calcium intake were evaluated.

RESULTS

At trimester 3, inverse associations between 1,25(OH)₂D and VO+ were evident in the Baltimore (P = 0.059) and Brazil (P = 0.008) cohorts and in the whole group (P = 0.029); calcium intake was not a significant determinant of VO+ in any group during pregnancy. At postpartum, a significant positive association was evident between VO+ and calcium intake (P ≤ 0.002) and between VO+ and African ethnicity (P ≤ 0.004) in the whole group and within the Baltimore and Brazil cohorts.

CONCLUSIONS

Elevated 1,25(OH)₂D was associated with decreased rates of bone calcium deposition during late pregnancy, a finding that was particularly evident in pregnant adolescents and adult women with low calcium intakes. Higher dietary calcium intakes and African ethnicity were associated with elevated rates of bone calcium deposition in the postpartum period.

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

Objective

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

Methods

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

Results

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

Conclusion

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

Lack of evidence for prescription of antepartum bed rest

Antepartum bed-rest treatment is based on assumptions that it is both effective and safe for mother and fetus. However, research indicates, that bed-rest treatment is ineffective for preventing preterm birth and fetal growth restriction, and for increasing gestational age at birth and infant birthweight. Studies of women treated with pregnancy bed-rest identify numerous side effects, including muscle atrophy, bone loss, weight loss, decreased infant birthweight in singleton gestations and gestational age at birth, and psychosocial problems. Studies conducted by aerospace scientists who have used bed rest as a model for the study of weightlessness in space using nonpregnant individuals report similar results. Antepartum bed-rest treatment should be discontinued until evidence of effectiveness is found.

Hypoestrogenism in young women and its influence on bone mass density

One of the most important hormonal factors responsible for bone health is estradiol. Genetic factors, adequacy of hormonal functioning, nutrition and physical activity may be the markers of bone status and development in young women. During adolescence, women reach peak bone acquisition and develop a skeletal mass. This process is largely regulated by endocrine factors mainly such as adequate levels of gonadal, adrenal and pituitary hormones. The crucial role played by estradiol and its impact on bones are very multiple. Estradiol induces growth factors' activation, receptor activator of nuclear factor kappa B ligand (RANKL) production inhibition and is mainly referred to antiresorptive activity. Clinical situations leading to hypoestrogenism has been linked to decreased bone mineral density leading to osteopenia and osteoporosis. This status both in fertile and perimenopausal women can increase the risk of pathological fractures. Such conditions as hypothalamic-pituitary insufficiency (functional hypothalamic amenorrhea, anorexia nervosa, Kallmann syndrome, hyperprolactinemia), ovarian failure (gonadal dysgenesis, premature ovarian failure) and iatrogenic treatment (surgery, chemotherapy, radiotherapy) can cause hypoestrogenism. The treatment of osteopenia and osteoporosis caused by hypoestrogenism is very essential and multidirectional. The crucial role of the therapy is the achievement of proper serum estradiol concentration and eliminate the causes of hypoestrogenism.

Blood lead levels among pregnant women: historical versus contemporaneous exposures

Blood lead among pregnant women, even at modest levels, may impair offspring cognitive development. We examine whether blood lead levels (BLLs) result from current versus historic exposures, among a cohort of pregnant women. Cumulative logit models were used to characterize the relationship between maternal risk factors and higher BLLs. Maternal blood lead levels more likely result from lead remobilization from historic versus contemporaneous exposures. Even if all lead sources were abated immediately, women and their fetuses would experience lead exposure for decades. This work emphasizes the importance of addressing sources of environmental lead exposure in the United States and internationally.

Postpartum bone status in teenage mothers assessed using peripheral quantitative computed tomography

Teenage pregnancy occurs during a time when the maternal skeleton may still be accruing mineral. We hypothesized that teenage mothers would have reduced amounts of bone mineral and altered bone geometry compared with controls. This cross-sectional, observational compared teenage mothers (n=18) to age- and ethnicity-matched controls (n=52). The main outcomes were peripheral quantitative computed tomography and dual-energy X-ray absorptiometry to measure bone geometry, bone mineral density (BMD) at radius, lumbar spine and hip, and whole body bone mineral content (WBBMC). In teenage mothers, cortical BMD was reduced at the radial diaphysis (mean difference: -1.3%; p=0.03). Size-adjusted WBBMC was reduced (mean difference: -4.0%; p=0.004) and was lower for a given amount of lean mass (mean difference: -5.8%; p=0.02). No other significant differences between groups were found. The recruitment and retention of participants to this study were extremely difficult and disappointing. Teenage mothers had lower BMD at cortical sites compared with age-matched controls. These data suggest that pregnancy might have a detrimental effect on teenage mothers' future skeletal health. The results of this study require confirmation and provide pilot data for further investigations.

Bone mineral density in adolescent females using injectable or oral contraceptives: a 24-month prospective study

OBJECTIVE

To determine whether bone mineral density (BMD) is lower in hormonal-contraceptive users than in an untreated comparison group.

DESIGN

Observational, prospective cohort; 24-month duration.

SETTING

Adolescent clinics in a metropolitan Midwestern setting.

PATIENT(S)

Four hundred thirty-three postmenarcheal girls, 12-18 years of age, who were on depot medroxyprogesterone acetate (DMPA; n = 58), were on oral contraceptives (OCs; n = 187), or were untreated (n = 188).

INTERVENTION(S)

Depot medroxyprogesterone acetate and OCs containing 100 microg of levonorgestrel and 20 microg of ethinyl E(2).

MAIN OUTCOME MEASURE(S)

Measurements of BMD at spine and femoral neck were obtained by using dual x-ray absorptiometry at baseline and 6-month intervals.

RESULT(S)

Over 24 months, mean percentage change in spine BMD was as follows: DMPA, -1.5%; OC, +4.2%; and untreated, +6.3%. Mean percentage change in femoral neck BMD was as follows: DMPA, -5.2%; OC, +3.0%; and untreated, +3.8%. Statistical significance was found between the DMPA group and the other two groups. In the DMPA group, mean percentage change in spine BMD over the first 12 months was -1.4%; the rate of change slowed to -0.1% over the second 12 months. No bone density loss reached the level of osteopenia.

CONCLUSION(S)

Adolescent girls receiving DMPA had significant loss in BMD, compared with bone gain in the OC and untreated group. However, the clinical significance of this finding is mitigated by slowed loss after the 1st year of DMPA use and general maintenance of bone density values within the normal range in the DMPA group.

Pregnancy-related hip diseases: incidence and diagnoses

BACKGROUND

Pregnancy-related hip diseases epidemiology has been poorly evaluated. We report our experience of gestational and postpartum hip diseases and evaluate their incidence.

METHODS

(1) Prospective survey: all pregnant or early postpartum women suspected to have hip involvement during their follow-up in an Obstetric unit were referred to a rheumatologist. If clinically confirmed, magnetic resonance imaging (MRI) and additional investigations as needed were performed. This survey had 2 years duration. (2) Retrospective study: all cases of definite (with MRI confirmation) pregnancy-related hip disease referred to our Rheumatology unit during the past 15 years were analyzed.

RESULTS

During the 2-year prospective survey, 3 patients (4 hips) of pregnancy-related hip disease were observed over 4900 pregnancies (1 case of transient osteoporosis of the hip (TOH) and 2 cases of occult fracture of the femoral head). During the 15-year retrospective study, 12 patients (17 hips) with hip diseases during pregnancy or early postpartum were identified. There were 6 patients (9 hips) with TOH, 4 patients (6 hips) with occult fracture of the femoral head, 1 patient with osteonecrosis of the femoral head, and 1 coxitis in a patient with ankylosing spondylitis. Differentiating diagnosis between TOH and occult fractures could only be made by MRI. Five of the 6 women with TOH had osteopenia at the lumbar spine at dual energy X-ray absorptiometry (DEXA). The 4 women with occult fractures had either osteopenia or osteoporosis at the lumbar spine.

CONCLUSION

Hip diseases are infrequent during pregnancy and early postpartum. Transient osteoporosis of the hip and occult stress fractures of the femoral head appear the main causes and those diagnoses justify evaluation for an underlying bone fragility. Osteonecrosis is very rare in this setting.

Dietary calcium supplementation to lower blood lead levels in pregnancy and lactation

Pregnancy and lactation are states known to be accompanied by physiologically up regulated bone resorption in response to the calcium demands of the developing fetus and nursing infant. The role of calcium supplements in altering maternal responses to fetal demand for calcium is not fully understood. Exposure to the toxicant lead is known to pose a major hazard to fetal neurodevelopment and growth. Since >95% of maternal lead is stored in the bone, mobilization of cumulative maternal lead stores into the circulation represents an endogenous source of exposure, which may pose a significant hazard for the fetus and infant. Maternal dietary calcium supplementation has been associated with reductions in lead levels in both animal and human studies when administered during pregnancy and lactation. Therefore, supplementation of the maternal diet with calcium may represent an important secondary prevention strategy aimed not only at reducing circulating levels of lead in the mother but also at reducing lead exposure to the developing fetus and nursing infant.

Nutritional status in pregnant adolescents: a systematic review of biochemical markers

Adolescent pregnancy is a major public health challenge for many industrialized countries and is associated with significant medical, nutritional, social and economic risk for mothers and their infants. Despite this, relatively little is known about the nutritional status of this population. The aim of this paper was to conduct a systematic review of the current evidence relating to the biochemical markers of nutritional status of pregnant adolescents living in industrialized countries. Six papers were identified that fulfilled the inclusion criteria, the majority of which were conducted in the United States. The studies were of variable quality and most failed to control for potential confounders which may have strongly influenced the findings. Due to limited research, conclusions cannot be drawn about the zinc and calcium status of pregnant adolescents, and data on folate and vitamin B(12) status appeared conflicting. There was some consensus among studies, however, to suggest that indicators of anaemia and iron status were compromised in pregnant adolescents, particularly during the third trimester of pregnancy. Chronological age did not appear to influence nutritional status, although there was some evidence to suggest that increasing gynaecologic age may positively influence plasma ferritin levels. Current research is limited by sampling and measurement bias, and research is urgently required to address these limitations. Further consideration should also be made of the influence of the role of socio-economic support on pregnant adolescents' nutritional status. The achievement of improved nutrition in pregnancy among adolescents requires multidisciplinary collaborations of adolescent healthcare providers, academics, professional organizations, policymakers, industry and service users. Only once this is achieved can adolescent nutrition, and adolescent nutrition in pregnancy, be significantly and sustainably optimized.

Bone mineral density in postmenarchal adolescent girls in the United States: associated biopsychosocial variables and bone turnover markers

PURPOSE

During adolescence, bone formation prevails over resorption, resulting in accumulation of 40% of peak bone mass throughout this time period. Although multiple studies have explored bone mass accrual during the early stages of puberty, less is known about factors that may influence bone accrual during later years of adolescence. In the present cross-sectional study we examined relationships among bone mineral density (BMD) and demographic factors, behavioral variables, and bone metabolism markers in postmenarchal adolescent girls.

METHODS

The population was comprised of 389 healthy postmenarchal adolescent girls aged 11-18 years, who were recruited into a prospective study of the effect of depot medroxyprogesterone acetate (DMPA) on bone health in adolescents. At the baseline visit, investigators collected demographic, reproductive health, and lifestyle data, and performed a complete physical examination. Body mass index (BMI) was calculated. Before study initiation, BMD at the lumbar spine, total hip, and femoral neck was measured by dual-energy X-ray absorptiometry (DXA), and markers of bone metabolism (serum bone-specific alkaline phosphatase [BAP], serum osteocalcin, and urinary N-telopeptide [uNTX]) were measured. The baseline data from this study were analyzed to evaluate possible correlates of BMD in postmenarchal adolescent girls. Potential associations between BMD values and other parameters were assessed by analysis of variance and Pearson's correlation coefficient.

RESULTS

Participants enrolled in the study had a mean (+/- SD) chronological age of 14.9 +/-1.7 years (range 11-18), mean gynecologic age of 39.9 +/-23.0 months (range 1-120) postmenarche, and mean BMI of 23.5 +/-4.6 kg/m(2) (range 16.0-42.2). Racial/ethnic distribution was 46% African American, 35% Caucasian, and 19% other races; 9% had previously been pregnant. Positive correlations were observed between lumbar spine BMD and chronological age (r = .301, p < .0001), gynecologic age (r = .349, p < .0001), and BMI (r = .371, p < .0001). Total hip and femoral neck BMD values were significantly higher (p < .05 and p < .05, respectively) in African American participants compared with non-African American participants. Previous history of pregnancy was significantly associated with a lower BMD at the lumbar spine (p < .0001) and the total hip (p < .01) when compared with the BMD of adolescents who had never been pregnant. Cigarette smoking and alcohol use were not associated with significant differences in BMD. Negative correlations were observed between gynecologic age and the levels of BAP (r = -.564, p < .0001), osteocalcin (r = -.349, p < .0001), and uNTX (r = -.281, p < .0001), and between lumbar spine BMD and BAP (r = -.363, p < .0001), osteocalcin (r = -.129, p < .05), and uNTX (r = -.202, p < .001) levels.

CONCLUSIONS

Our data demonstrate that chronological age, gynecologic age, race/ethnicity, BMI, and previous history of pregnancy are markedly associated with BMD in postmenarchal adolescent girls. Bone accretion in the postmenarchal years continues in the face of a slowdown in bone turnover during this time period.

Depot medroxyprogesterone acetate and bone mineral density in adolescents--the Black Box Warning: a Position Paper of the Society for Adolescent Medicine

The purpose of this Position Paper is to review the published Black Box Warning regarding depot medroxyprogesterone acetate (DMPA) and bone loss as it relates to adolescent girls. The scientific findings that prompted the Food and Drug Administration to issue the warning are reviewed and the following additional issues are considered: (1) likely low risk of fracture related to DMPA use, (2) evidence of at least partial recovery after discontinuation of the method, and (3) the need to balance the physical, social and economic cost of adolescent pregnancy versus the immediate and long-term impact of DMPA on bone. A list of clinical guidelines is included, the main recommendation of which is to continue prescription of DMPA, with counseling about the risks and benefits, in most of the adolescent population desiring to use this contraceptive method.

Calcium supplementation during pregnancy and lactation: effects on the mother and the fetus

Calcium consumption is essential for bone development and maintenance throughout life, yet more than one half of the female population in the United States does not consume the recommended amount of calcium. Calcium intake is especially crucial during pregnancy and lactation because of the potential adverse effect on maternal bone health if maternal calcium stores are depleted. There is often a transient lowered bone mineral density and increased rate of bone resorption, with the greatest consequence during the third trimester and throughout lactation. Studies indicate that calcium consumption should be encouraged, especially during pregnancy and lactation, to replace maternal skeletal calcium stores that are depleted during these periods. Because the fetus in utero and the neonate through breast-feeding are dependent on maternal sources for the total calcium load, adequate maternal calcium intake also can affect fetal bone health positively. Proper calcium consumption can be attained through the diet by the consumption of dairy products or leafy greens (such as kale), the consumption of fortified foods, or by supplementation with widely available calcium-containing supplement products. Because many women experience heartburn during pregnancy, calcium-based antacids are ideal for providing heartburn relief, and they offer a calcium supplement to ensure maternal and fetal bone health, without the danger of adverse effects on the neonate.

Maternal plasma osteoprotegerin concentration in normal pregnancy

OBJECTIVE

Pregnancy is associated with major changes in calcium metabolism because the neonatal skeleton contains approximately 30 g of calcium, which are largely deposited in the third trimester. Osteoprotegerin (OPG) acts as a decoy receptor for the "Receptor Activator of Nuclear Factor-kappaB Ligand" (RANKL), which is an essential factor for bone remodeling. This study was conducted to determine whether there were changes in maternal plasma OPG concentration during normal pregnancy.

STUDY DESIGN

A cross-sectional study was performed in 433 patients of reproductive age (40 nonpregnant and 393 pregnant). Pregnant patients were classified into 4 groups according to gestational age: group 1: 11 to 14 weeks (n = 100); group 2: 15 to 18 weeks (n = 99); group 3: 27 to 30 weeks (n = 100); and group 4: 37 to 42 weeks (n = 94). Plasma OPG concentrations were measured with the use of a sensitive and specific immunoassay. Nonparametric statistics were used for analysis.

RESULTS

OPG was detected in the plasma of all women tested. The median OPG concentration was significantly higher in term patients than in those in early pregnancy (median: 6.63 pmol/L [range: 1.57-25.57] vs median: 3.98 pmol/L [range: 0.41-13.71], P < .001). There was no significant difference in plasma OPG concentrations between nonpregnant women and those in groups 1 or 2 (nonpregnant women median: 3.86 pmol/L [range: 1.64-15.29] vs group 1 median: 3.98 pmol/L [range: 0.41-13.71] vs group 2 median: 3.87 pmol/L [range: 1.14-69.83], P = .75).

CONCLUSION

The median maternal plasma OPG concentration is higher in the third trimester than in the first trimester of pregnancy. OPG may be involved in the regulation of bone turnover during pregnancy.

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

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

Bed rest and other determinants of bone loss during pregnancy

OBJECTIVE

The purpose of this study was to evaluate patterns of bone loss during pregnancy and potential influences.

STUDY DESIGN

This was a prospective study of 181 women receiving prenatal care at Magee-Womens Hospital or its auxiliary clinics in Pittsburgh, Pennsylvania, between 1992 and 1995. Bone mineral density was measured at approximately 16 and 36 weeks' gestation.

RESULTS

Trabecular, but not cortical, bone loss occurred during pregnancy. Mean ultra-distal bone mineral density loss was 1.9% (95% CI 1.2-2.5) during the 20-week period. Women prescribed bed rest had an adjusted mean loss of 4.6% compared with 1.5% for women not prescribed bed rest ( P = .001) and 6-fold higher odds ( P = .001) of bone loss > or =5% during the 20-week period. Nulliparity, calcium intake < 2 000 mg/day, low weight gain, and maternal age < 21 or >30 years were more modestly associated with greater bone loss.

CONCLUSION

Substantial trabecular bone loss may occur during pregnancy, particularly in women prescribed bed rest. Study of postpartum bone recovery in such women is needed.

Do appendicular bone measurements reflect changes in the axial skeleton?: the use of dual-energy X-ray absorptiometry and ultrasound measurements during lactation

The ability of different bone measurement techniques to monitor changes in bone mineral was studied. Lactation was used as a model because large, rapid, but reversible decreases in bone mineral content (BMC) occur in breast-feeding women. Spine and forearm dual-energy X-ray absorptiometry (DXA) and calcaneal quantitative ultrasound (QUS) measurements were made during 30 lactations. During the first 3 mo of lactation, decreases in the BMC, adjusted for area, were significant at the spine (-2.8%; standard error [SE] = 0.6; p < 0.001) but not the wrist (p = 0.40). Nonsignificant increases in normalized broadband ultrasound attenuation (nBUA) and velocity of sound (VOS) were observed at the calcaneus using QUS. From peak lactation to postlactation, the BMC increases at the spine were significant (4.1%; SE = 0.6; p < 0.001) but not those at the wrist (p = 0.17). Nonsignificant decreases were observed using QUS. Eleven breast-feeding women had longitudinal calcaneal and spine DXA measurements from peak lactation to postlactation. Significant BMC increases were observed at both sites (calcaneus: 2.4%, SE = 0.7, p < 0.01; spine: 3.3%, SE = 1.3, p < 0.03). The similarity of DXA calcaneal changes to spine changes indicates that DXA calcaneal measurements could be a useful alternative tool when it is difficult to monitor BMC at axial sites.

Release of lead from bone in pregnancy and lactation

Concentrations and isotope ratios of lead in blood, urine, 24-h duplicate diets, and hand wipes were measured for 12 women from the second trimester of pregnancy until at least 8 months after delivery. Six bottle fed and six breast fed their infants. One bottle feeder fell pregnant for a second time, as did a breast feeder, and each was followed semicontinuously for totals of 44 and 54 months, respectively. Bone resorption rather than dietary absorption controls changes in blood lead, but in pregnancy the resorption of trabecular and cortical bone are decoupled. In early pregnancy, only trabecular bone (presumably of low lead content) is resorbed, causing blood leads to fall more than expected from hemodilution alone. In late pregnancy, the sites of resorption move to cortical bone of higher lead content and blood leads rise. In bottle feeders, the cortical bone contribution ceases immediately after delivery, but any tendency for blood leads to fall may be compensated by the effect of hemoconcentration produced by the postpartum loss of plasma volume. In lactation, the whole skeleton undergoes resorption and the blood leads of nursing mothers continue to rise, reaching a maximum 6-8 months after delivery. Blood leads fall from pregnancy to pregnancy, implying that the greatest risk of lead toxicity lies with first pregnancies.

The impact of reproductive and menstrual history on bone mineral density in Chinese women

Low bone mineral density (BMD) is an important risk factor for osteoporotic fractures. The impact of gynecological history on BMD is of great concern, but the results are largely inconsistent. In this study, we investigated the association of gynecological history with BMD in 214 postmenopausal women (60.4 +/- 5.7 yr), as well as with peak bone density (PBD) in 428 premenopausal women (30.8 +/- 5.3 yr) from Shanghai City in China. BMD was measured at lumbar spine (L1-4) and total hip by dual energy X-ray absorptiometry. Raw BMD values were adjusted by age, age2, height, and weight. In the postmenopausal group, more parity had significantly detrimental effects on BMD at both the spine and hip (p < 0.01). The age of the first delivery, the duration of lactation, and the age at menarche did not show significant impacts on BMD (p > 0.05). More years since menopause only had marginally significant decreasing effects at the spine (p = 0.09), but not at the hip (p > 0.10). In the premenopausal group, none of the three reproductive factors had significant impact on PBD (p > 0.05); the age of menarche inversely affected PBD at both the spine (p < 0.01) and hip (p < 0.05). Our results suggest that some gynecological events might influence BMD variation in healthy Chinese women.

Lead in breast milk and maternal bone turnover

OBJECTIVE

Our purpose was to determine whether breast milk lead (Pb) levels are correlated with maternal blood Pb levels, bone loss, or bone turnover during reproduction.

STUDY DESIGN

Data were collected prospectively at 0, 1.5, 3, 6, and 12 months after delivery in 15 lactating and 30 bottle-feeding women. Variables included breast milk Pb (inductively coupled mass spectrometry), maternal blood Pb (atomic absorption spectrophotometry), osteocalcin (radioimmunoassay), and bone mineral density change (dual-energy x-ray absorptiometry).

RESULTS

Mean Pb breast milk concentrations were 6.1, 5.6, 5.9, and 4.3 ng/mL at the 1.5, 3, 6, and 12 months post partum, whereas mean maternal blood Pb concentrations were 1.4, 1.6, 1.7, and 1.4 microg/dL at 0, 3, 6, and 12 months post partum. The 5.6% bone loss and significant bone turnover were related to breast milk Pb levels but not to postpartum maternal blood Pb levels. Maternal and breast milk Pb values were modestly correlated at 1 to 2 months.

CONCLUSIONS

Bone loss and bone turnover were related to breast milk Pb levels. In these women, there was no evidence that either high maternal blood or breast milk Pb concentrations are a major public health concern.

Effect of pregnancy on bone mineral density in healthy women

Despite numerous studies and case reports of changes in bone mineral density (BMD) during pregnancy, the postpartum, and lactation, controversy exists regarding the time course of BMD changes and recovery to baseline levels. The degree to which pregnancy affects BMD long-term remains unclear. Several influencing factors, including breast-feeding, length of amenorrhea after pregnancy, and parity, have been studied with respect to changes in BMD in healthy women. We conducted the first systematic review of its kind on this topic and evaluated the 23 identified citations according to the U.S. Preventive Services Task Force rating scale. Six studies qualified as Level II-2, 12 were Level II-3, and 5 were Level III. There seems to be good evidence that calcium is mobilized from the maternal skeleton to that of the developing fetus during pregnancy. However, the eventual return of BMD to prepregnancy values suggests that maternal bone loss may not be permanent. Results from the studies that specifically evaluated the effect of lactation on BMD were varied, ranging from a decrease in BMD to no change. Of the studies that evaluated the effect of parity on BMD, none found an association linking a greater number of pregnancies to greater decreases in BMD. Pregnancy-associated osteoporosis seems to be uncommon, based on the limited published reports. Overall, no long-term adverse clinical effects have been noted in healthy women who had at least one ongoing pregnancy, despite the good evidence that some bone loss does occur soon after delivery. Additional longitudinal studies need to be undertaken to provide more definitive information on the effects of pregnancy on BMD and risk of osteoporosis later in life.